compare lowercase on albumartist display
Merge pull request #321 from hurzl/upstr

compare lowercase on albumartist display
Simplify cover API : Remove the cacheOnly parameter.
Make the API simpler and was always set to false.
Refactor the PlaylistFragment to use the Music model objects  instead of strings
Refactor cover download API : use AlbumInfo everywhere
Improve Playlist for streams
Use the android TextUtils method instead of the custom StringsUtils.isNullOrEmpty()
Add progressbars to albums and album grid fragments
Display progress bar in the nowplayingsmall fragment when changing a cover
Add progress bar to the album view when changing cover
Use artist instead of albumartist when albumartist is missing
Update the nowplaying cover on resume when you change the cover in the library activity.
Minor update : change the album key
Improve playlist fragment
- Do not refresh the whole playlist when the current playing song changes
- Reintroduce the "No Cover" bitmap when a cover is downloaded (avoid to display the previous wrong cover)
- Do not re-download item covers
- Add a method to refresh a single song view in the playlist