Revert "Partial Revert"

This reverts commit dd47289071014dedb3075d9f2895ab009f9cdec4.
Revert "Reduce observers in SystemUI: KeyButtonView"

This reverts commit a685eccb621745b2b1776b16f753b354d8b7b7a6.
Reduce observers in SystemUI: KeyButtonView

This is based on the work by Jens Doll for the StatusBarIconView

The ContentObserver class will be a singleton, so there is only
one observer for all buttons.

On my Nexus 10 it reduced the observer count from 48 to 4.

This version fixes the funky glow effect.

Change-Id: Ie242e3771c41f6010ac12246372107a2a3e165cd
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>

Conflicts:

	packages/SystemUI/src/com/android/systemui/statusbar/policy/KeyButtonView.java
Partial Revert

Fixing Build temporarily