feature #558 Update Composer dependencies (bocharsky-bw)

This PR was squashed before being merged into the master branch (closes #558).

Discussion
----------

Update Composer dependencies

After the new v3.2.8 Symfony release

```text
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 0 installs, 16 updates, 0 removals
  - Updating erusev/parsedown (1.6.1 => 1.6.2): Downloading (100%)
  - Updating ezyang/htmlpurifier (v4.9.1 => v4.9.2): Downloading (100%)
  - Updating twig/twig (v1.32.0 => v1.33.2): Downloading (100%)
  - Updating paragonie/random_compat (v2.0.9 => v2.0.10): Loading from cache
  - Updating symfony/symfony (v3.2.5 => v3.2.8):  Checking out 85959c2abb
  - Updating sensio/distribution-bundle (v5.0.18 => v5.0.19): Downloading (100%)
  - Updating sensio/framework-extra-bundle (v3.0.23 => v3.0.25): Loading from cache
  - Updating monolog/monolog (1.22.0 => 1.22.1): Loading from cache
  - Updating symfony/monolog-bundle (v3.0.3 => v3.1.0): Loading from cache
  - Updating swiftmailer/swiftmailer (v5.4.6 => v5.4.8): Downloading (100%)
  - Updating symfony/swiftmailer-bundle (v2.5.3 => v2.5.4): Loading from cache
  - Updating dama/doctrine-test-bundle (v1.0.12 => v1.0.13): Downloading (100%)
  - Updating friendsofphp/php-cs-fixer (v2.1.1 => v2.2.3): Downloading (100%)
  - Updating sensio/generator-bundle (v3.1.3 => v3.1.4): Loading from cache
  - Updating symfony/phpunit-bridge (v3.2.5 => v3.2.8): Downloading (100%)
  - Updating pagerfanta/pagerfanta (v1.0.4 => v1.0.5): Loading from cache
```

Commits
-------

4a7f08d Update Composer dependencies

Author: javiereguiluz