Remove VolumeBar if MPD returns -1
whitespace fix
added the re-appearance volumebar
Merge pull request #410 from philchand/Volume-Bar-remove

Volume bar remove when MPD get volume returns -1 (no volume control)
avoid NPE in Music.getPath()
remove albumartist user option and make getAlbums return merged lists
Go to Album Artist in NowPlaying
add albumCache and cachedMPD
replace MPD by CachedMPD (without enabling it)
add option whether to use local album cache
allow AlbumsGridFragment for full album list when using cache
 move Artist.isAlbumArtist to Album.hasAlbumArtist
 use hasAlbumArtist for AlbumDetails in AlbumCache
remove Artist from SongsFragment
compare by isSameOnList in Item.merged()
check for hasAlbumArtist in Album.isSameOnList
fix sorting albums by artists and albumartists
adjust Searchactivity
Override listAlbumArtists in CachedMPD
show artists in albums list