Added Roles Trait and refactored Artist and Movie
Merge remote-tracking branch 'origin/master' into roles-refactor

Conflicts:
	src/Myclapboard/ArtistBundle/Model/Artist.php
	src/Myclapboard/ArtistBundle/Model/ArtistInterface.php
	src/Myclapboard/MovieBundle/Model/Movie.php
	src/Myclapboard/MovieBundle/Model/MovieInterface.php
Finished Roles' refactor