implementing parts of "Official Symfony Best Practices"
renamed services to be shorter
moved ApiBundle into new AppBundle
moved AdminBundle to AppBundle
Moved code parts from TestBundle to AppBundle
moved CoreBundle config to app/
moved status codes to appbundle
moved events to appbundle
moved exceptions to appbundle
moved models, services and listeners to appbundle
moved specs into root directory
moved AppBundle to namespace
moved Entities to AppBundle
updated vendors
removed unused code
moved language listener to appbundle
Merge branch 'dev-master' into best_practice_guide
Merge branch 'best_practice_guide' of https://github.com/Catrobat/Catroweb-Symfony into best_practice_guide