Edited IntegrateRemoteCatalogCommand so the "Long mPeerId" parameter is now a "Peer mPeer"
- IntegrateRemoteCatalogCommand : filled execute function, next step : implementing the corresponding method in MusicService
- RemoveFromLocalCatalogCommand : edited List<Music> to Collection<Music> to fit the parameter type of the command, filled execute function, next step : implementing the corresponding method in MusicService
- AddToLocalCatalogCommand : edited List<File> to Collection<File> to fit the parameter type of the command, filled execute function, next step : implementing the corresponding method in MusicService