[Android] Delete unused ViewModel classes

[Geoffrey Métais]

vlc-android | branch: master | Geoffrey Métais <geoffrey.metais at gmail.com> | Fri May  3 14:55:03 2019 +0200| [34470c84026aafc73a75af88b51aeccf6cf6fbef] | committer: Geoffrey Métais

Delete unused ViewModel classes

> https://code.videolan.org/videolan/vlc-android/commit/34470c84026aafc73a75af88b51aeccf6cf6fbef
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 .../videolan/vlc/viewmodels/audio/AlbumModel.kt    | 79 -------------------
 .../videolan/vlc/viewmodels/audio/ArtistModel.kt   | 77 ------------------
 .../videolan/vlc/viewmodels/audio/AudioModel.kt    | 27 -------
 .../videolan/vlc/viewmodels/audio/GenresModel.kt   | 73 ------------------
 .../vlc/viewmodels/audio/PlaylistsModel.kt         | 70 -----------------
 .../videolan/vlc/viewmodels/audio/TracksModel.kt   | 90 ----------------------
 6 files changed, 416 deletions(-)

Diff:   https://code.videolan.org/videolan/vlc-android/commit/34470c84026aafc73a75af88b51aeccf6cf6fbef