change to setFallbackLocales

tested in symfony2.3, and it asked for setFallbackLocales instead
Merge branch 'master' of github.com:ihsanfaisal/testing-bundle into ihsanfaisal-master

* 'master' of github.com:ihsanfaisal/testing-bundle:
  change to setFallbackLocales
Updated composer.json for Symfony 2.3
Updated README for Symfony 2.3