Add Composer's auto-clean support

Cleans cache on composer install / composer update.

```
ninsuo:project alain$ composer update
Loading composer repositories with package information
Updating dependencies (including require-dev)
Nothing to install or update
Writing lock file
Generating autoload files
Updating the "app/config/parameters.yml" file
Clearing the cache for the dev environment with debug true
Installing assets as symlinks
Installing assets for Symfony\Bundle\FrameworkBundle into web/bundles/framework
Installing assets for Fuz\AppBundle into web/bundles/fuzapp
Installing assets for Sensio\Bundle\DistributionBundle into web/bundles/sensiodistribution
Web: Clear APC User Cache: success Opcode Cache: success. Reset attempts: 1.
ninsuo:project alain$ 
```