Keyguard: fixup background options

-fix transparency
-heed to album art override during music playback

Change-Id: I5836b519c82c9e8126007b14172a9075041f2ae0
SystemUi: update 6bar drawables

same icons renamed (they were backwards)

Change-Id: I5ce9115ccfad16df19e9f3e2ec230e4531007721
Merge branch 'ev/kitkat'