[1/2] Base: Battery Saver mode

Change-Id: I9d86ef1425228e11cadd85d37c5b6e8b20e50fb0
Trimmed down lots of other battery saver mods[1/2]

Change-Id: I075074917fccd80dd756fc1e525f2bf75582ecb8

Conflicts:
	packages/SystemUI/src/com/android/systemui/batterysaver/KillAllModeChanger.java
	packages/SystemUI/src/com/android/systemui/statusbar/policy/BatteryController.java
	packages/SystemUI/src/com/android/systemui/statusbar/policy/BluetoothController.java
	services/java/com/android/server/NotificationManagerService.java