- Untrack Gemfile.lock
- Move `inch` gem from Gemfile to development dependency in gemspec

Details:
https://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/

Try to restore CI

add warning for `config.docs_dir`

…pmark#458)

* Allow response_body_formatter config to format "binary" responses

Following this issue on Rack's repository:
[Fix incorrect MockResponse#body String encoding](rack/rack#1486), it looks like we can expect, from now on, that Rack's `response_body` encoding will be `Encoding::ASCII_8BIT`:

> I think the response body should probably always be ASCII-8BIT. Rack
can't really know anything about the encoding of the bytes that users
want to send. At the end of the day, it's just bytes written to the
socket, and I don't think Rack should have any opinion about the
encoding the user sends.

Therefore, `rspec_api_documentation` cannot rely on
`response_body.encoding` to determine whether the response is binary
data or not. This line becomes incorrect:

https://github.com/zipmark/rspec_api_documentation/blob/81e5c563ce6787f143cf775c64e2bd08c35d3585/lib/rspec_api_documentation/client_base.rb#L90-L91

The real fix would be to figure out a better way to define whether a
string is binary or not, but I believe this is a bit outside the scope of my
knowledge.

In this PR, I'm focusing on giving any application using the
`rspec_api_documentation` the choice on how to process the
response_body, and particularly on how to detect binary data, while not
altering `rspec_api_documentation`'s default behaviour.

As an additional benefit, this change would allow an application to
display friendlier responses in the documentation for some binary types.

For example, PNG data:

```rb
Proc.new do |content_type, response_body|
  # http://www.libpng.org/pub/png/spec/1.2/PNG-Rationale.html#R.PNG-file-signature
  if response_body[0,8] == "\x89PNG\r\n\u001A\n"
    "<img src=\"data:image/png;base64,#{Base64.strict_encode64(response_body)}\" />"
  elsif content_type =~ /application\/.*json/
    JSON.pretty_generate(JSON.parse(response_body))
  else
    response_body
  end
end
```

* Update README.md

Co-Authored-By: Benjamin Fleischer <[email protected]>

This change is part of preliminary efforts at attempting to refresh
the Continuous Integration setup, by supporting recent Ruby version and
updating dependencies.

To be honest, I don't know what benefits the Thin server brings to the table.
I tried digging in the code, but the commit that introduced it does not
tell me much: cdeea8b.

What I know however is that I have troubles running the specs locally,
getting a timeout on this line:

https://github.com/zipmark/rspec_api_documentation/blob/560c3bdc7bd5581e7c223334390221ecfc910be8/spec/http_test_client_spec.rb#L16

However, letting Capybara handle its server details, as shown in this PR,
does not seem to have any negative impact (spec is still green, and fairly fast).

> `root`: deprecated key `sudo` (The key \`sudo\` has no effect anymore.)

* Test more recent versions of Ruby on Travis

Added:
- 2.4.9 (reached end-of-life but may temporarily help in incremental debugging)
- 2.5.8
- 2.6.6

Did not add 2.7.x yet because it introduces *a lot* of warnings.

Did not remove any past version yet because until decided otherwise,
they should be supported by the gem. (I would recommend a major version
bump when those versions get dropped.)

The idea is that developments from now on should be future-proof, and
changes should be tested on current versions of Ruby.

* Update WebMock to latest 2.x version

Updating to WebMock 2.x means that:

> require 'webmock' does not enable WebMock anymore. gem 'webmock' can
now be safely added to a Gemfile and no http client libs will be
modified when it's loaded. Call WebMock.enable! to enable WebMock.
>
> Please note that require 'webmock/rspec', require 'webmock/test_unit',
require 'webmock/minitest' and require 'webmock/cucumber' still do
enable WebMock.

Source: [WebMock's
CHANGELOG.md](https://github.com/bblimke/webmock/blob/master/CHANGELOG.md#200).

As rspec_api_documentation is very much tied to RSpec, I saw no problem
with replacing all instances of `require 'webmock'` with `require
'webmock/rspec'`.

* Update WebMock dependency to 3.2.0

3.2.0 introduced another breaking change that had to be addressed:

[Automatically disable WebMock after rspec suite](bblimke/webmock#731)

As the example app_spec.rb in features/oauth2_mac_client.feature is supposed to be a stand-alone spec file, it made sense, to me, to `require "webmock/rspec"`.
Does that make any sense?

* Bump WebMock dev dependency to 3.5.0

This introduces Ruby 2.6 support and should get the test suite to run on that version of Ruby.

* Try using WebMock 3.8.3

Let's see how this goes on Travis.

> ### Why is Gemnasium.com closed?
> Gemnasium was acquired by GitLab in January 2018. Since May 15, 2018, the services provided by Gemnasium are no longer available.

[Source.](https://docs.gitlab.com/ee/user/project/import/gemnasium.html#why-is-gemnasiumcom-closed)

Why:
Trying run the specs on vanilla machine produces error:
```
resource.rb:10:in `block in define_action: undefined method extract_options! for ["/path"]:Array (NoMethodError)
```

Why:
Trying to run specs with the old version using `bundle exec rspec` leads to an error:
```
tried to create Proc object without a block
faraday-0.9.2/lib/faraday/options.rb:153:in new:
tried to create Proc object without a block (ArgumentError)
...
../http_test_client.rb:2:in require
```

Why:
Fixes error when running specs `bundle exec (/home/m/.rbenv/versions/3.1.0/bin/rspec)
bundle exec rspec spec/dsl_spec.rb`
```
NoMethodError:
undefined method `stringify_keys for {:name=>"Friday Order"}:Hash
...
dsl/endpoint.rb:171:in `block in extra_params
```

Why:
Given specs fails on expecting `description` field being empty while
in current version it contains capitalised version of `name` attribute.
```
       expected: [{:required=>false, :name=>"description", :description=>nil, :properties_description=>"optional"}]
            got: [{:required=>false, :name=>"description", :description=>"Description", :properties_description=>"optional"}]
```

Support for Ruby 3.2

test: Switch to GitHub actions

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Updates the requirements on [rack-oauth2](https://github.com/nov/rack-oauth2) to permit the latest version.
- [Release notes](https://github.com/nov/rack-oauth2/releases)
- [Changelog](https://github.com/nov/rack-oauth2/blob/main/CHANGELOG.md)
- [Commits](nov/rack-oauth2@v1.2.2...v1.12.0)

---
updated-dependencies:
- dependency-name: rack-oauth2
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Updates the requirements on [rspec](https://github.com/rspec/rspec-metagem) to permit the latest version.
- [Commits](rspec/rspec-metagem@v3.4.0...v3.13.0)

---
updated-dependencies:
- dependency-name: rspec
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

…/actions/checkout-4

Bump actions/checkout from 2 to 4 [ci skip]

…auth2-tw-1.12.0

Update rack-oauth2 requirement from ~> 1.2.2 to ~> 1.12.0 [ci skip]

…tw-3.13.0

Update rspec requirement from ~> 3.4.0 to ~> 3.13.0 [ci skip]

…tw-0.14.14

Update aruba requirement from ~> 0.13.0 to ~> 0.14.14 [ci skip]

Updates the requirements on [contracts](https://github.com/egonSchiele/contracts.ruby) to permit the latest version.
- [Changelog](https://github.com/egonSchiele/contracts.ruby/blob/master/CHANGELOG.markdown)
- [Commits](egonSchiele/contracts.ruby@v0.13.0...v0.17)

---
updated-dependencies:
- dependency-name: contracts
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

…cts-tw-0.17

Update contracts requirement from ~> 0.13.0 to ~> 0.17 [ci skip]

Updates the requirements on [multi_json](https://github.com/intridea/multi_json) to permit the latest version.
- [Changelog](https://github.com/intridea/multi_json/blob/master/CHANGELOG.md)
- [Commits](intridea/multi_json@v1.11.2...v1.15.0)

---
updated-dependencies:
- dependency-name: multi_json
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Updates the requirements on [rspec-its](https://github.com/rspec/rspec-its) to permit the latest version.
- [Changelog](https://github.com/rspec/rspec-its/blob/main/Changelog.md)
- [Commits](rspec/rspec-its@v1.2.0...v1.3.0)

---
updated-dependencies:
- dependency-name: rspec-its
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

…json-tw-1.15.0

Update multi_json requirement from ~> 1.11.2 to ~> 1.15.0 [ci skip]

Updates the requirements on [capybara](https://github.com/teamcapybara/capybara) to permit the latest version.
- [Changelog](https://github.com/teamcapybara/capybara/blob/master/History.md)
- [Commits](teamcapybara/capybara@2.6.2...3.39.2)

---
updated-dependencies:
- dependency-name: capybara
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

…ra-tw-3.39.2

Update capybara requirement from ~> 2.6.2 to ~> 3.39.2 [ci skip]

…its-tw-1.3.0

Update rspec-its requirement from ~> 1.2.0 to ~> 1.3.0 [ci skip]

Updates the requirements on [rake](https://github.com/ruby/rake) to permit the latest version.
- [Release notes](https://github.com/ruby/rake/releases)
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)
- [Commits](ruby/rake@v10.5.0...v13.2.1)

---
updated-dependencies:
- dependency-name: rake
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Updates the requirements on [sinatra](https://github.com/sinatra/sinatra) to permit the latest version.
- [Changelog](https://github.com/sinatra/sinatra/blob/main/CHANGELOG.md)
- [Commits](sinatra/sinatra@v1.4.7...v2.0.8.1)

---
updated-dependencies:
- dependency-name: sinatra
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

…a-tw-2.0.8

Update sinatra requirement from ~> 1.4.7 to ~> 2.0.8 [ci skip]

Updates the requirements on [gherkin](https://github.com/cucumber/cucumber) to permit the latest version.
- [Release notes](https://github.com/cucumber/cucumber/releases)
- [Commits](cucumber/common@react/v3.2.0...gherkin/v9.0.0)

---
updated-dependencies:
- dependency-name: gherkin
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

…w-13.2.1

Update rake requirement from ~> 10.5.0 to ~> 13.2.1 [ci skip]

Updates the requirements on [webmock](https://github.com/bblimke/webmock) to permit the latest version.
- [Changelog](https://github.com/bblimke/webmock/blob/master/CHANGELOG.md)
- [Commits](bblimke/webmock@v3.8.3...v3.23.0)

---
updated-dependencies:
- dependency-name: webmock
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

…k-tw-3.23.0

Update webmock requirement from ~> 3.8.3 to ~> 3.23.0 [ci skip]

…n-tw-9.0.0

Update gherkin requirement from ~> 3.2.0 to ~> 9.0.0 [ci skip]

…tation into nicolaa-master

…cumentation into keram-failing-specs