Merge pull request #422 from jibzou/master

[Music - hebergui] Correction SongRater getUserId
Modification après correction d'une issue de Music
Merge pull request #423 from hebergui/BRANCHE_rate-song

[IHM] Modification après correction d'une issue de Music
integ 17/12 #1
Merge pull request #424 from Lowess/Integration_RemoteMusic

integ 17/12 #1
[Music] Delete a song + Save a distant song implementation
-> ApiMusicImpl & ApiMusic => Methods implementation
-> SongLoader => SaveSong + static variable songsToDownload + getSavedSongPath