LevelScreen&Animation missing, rest done, except GameEntity and InfiniteBackground that Thomas is in charge of
Merge branch 'master' of https://www.github.com/Team-image-intensif-2014-2015/projet-intensif-image-2015
Merge branch 'master' of https://github.com/obodrel/projet-intensif-image-2015
Fixation correct de la taille du canvas