JMPDComm: Move the unknown translations back to JMPDComm.

Move the unknown metadata translations back into JMPDComm using standard Java
internationalization.
Music: If albumartist or artist is not available, use unknown artist.
ignore case when comparing Strings for Music sorting
don't sort Music by disc and track number for searches, but everywhere else
fix String comparison
fix Album Artist not showing on SongsFragment

fixes #626
Add some material design

Also fix old style declaration style
Settings are now light
Use material blue, add statusbar coloration
Add supportv7 for more material goodness
v7 Actionbar toggle
More material colors
Fix wrong colors
Fix the colors
Remove L actionbar shadow
Fix dark mode colors
Light theme is now the default theme
gradle: Maven central isn't necessary for JMPDComm.
Artist: Remove broken method for name comparison.

This should fix #625.

This fixes a bug which was uncovered when the equals() method in the Artist
item was fixed in 51cecb7.
Various fixes