travis CI

[kazu-yamamoto]

Currently, travis CI runs GHC 7.4, 7.6, 7.8, 7.10, 8.0 and 8.2 with cabal new-build. Here are what we should do:

• Using cabal-install-2.0 instead of cabal-install-head. (Update travis with cabal 2.0 and ghc head #272)
• Using cabal build in addition to cabal new-build
• Getting doctest back
• Using cabal version 2 instead of head

[kazu-yamamoto]

I would like to close the following issues in favor of this issue:

• WIP: Use cabal-doctest #245
• Update Travis CI script #254
• Regenerate .travis.yml #259

Let's start over.

[eborden]

Closing as this issue is out of date.