fixed deprecation error about addCollection
using spaces instead of tabs for the indentation
fixing travis setup
Merge remote-tracking branch 'simonchrz/master' into travis

* simonchrz/master:
  using spaces instead of tabs for the indentation
  fixed deprecation error about addCollection
disable 2.3 ak dev-master because of SensioFrameworkExtraBundle
Merge pull request #393 from FriendsOfSymfony/travis

fixing travis setup
droped 2.0 support
updated branch alias