Add BAMF theme engine

Thanks to travp624 @ TeamBaked for originally porting this

Change-Id: I9dd9347ac62e3b1fb49a4562d84eb7b295cdc2b2
Revert "Reduce observers in SystemUI: KeyButtonView"

Temporary revert. We will get back to you, observers.

This reverts commit 855f54384d99242bcc25a0de7cfb6c104035b034

Change-Id: If612ee7ca947f5f00bd42d2d45205f50ba2f979d
Merge "Revert "Reduce observers in SystemUI: KeyButtonView"" into jb-mr1
Merge remote-tracking branch 'upstream/jb-mr1' into jb-mr1