Framework: Port notification drawer custom background (2/2)

Patchset 2
- one small correction

Change-Id: I017bf281426fbf3c5f0525dde81a43bef60c7193

Conflicts:
	core/java/android/provider/Settings.java
Framework: Add notification rows transparency (2/2)

Patchset 2+3
-rebased

Change-Id: Ifdca707989fe836a2a0b46869da808e0750494d8
Configurable Notification Behavior [2/2]

PS 2 : Cleanup

Credit: Michele Primavera

Change-Id: I7693b05c6938e979e7d7735c0eff3a5018b81967