Avoid crash when removing an album from playlist

Crash with NPE when going thru the playlist and finding a song without album defined.
more crashproof album deletion
more crashproof album deletion
Merge pull request #314 from hurzl/upstream

more crashproof album deletion
ViewPager is back
Tablet fix
Fixed drawer stack popping bug
Album details triangle has a bigger hitbox
Bigger hitbox for the song handle (for reordering).
Better looking queue layout (when the handle is hidden the cover is not stuck on the left anymore)
Cover art is now used for reordering the queue
"No Results" doesn't show up in the wrong lists in search results. Refs #301
Implemented PagerAdapter correctly. Fixes #301
add ".." (parent directory) to file browser
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
Merge pull request #317 from hurzl/newup

add ".." (parent directory) to file browser
name the apk MPDroid instead of MainAcitvity
show album artist on NowPlaying and according cover
don't show artist if empty, don't show both if albumarist==artist