Framework: Quiet Hours System Sounds (1/2)

Change-Id: I52c79a9fec98b5c75f88fc644766e830d5f6148e

Conflicts:
	packages/SystemUI/src/com/android/systemui/screenshot/GlobalScreenshot.java

Conflicts:
	core/java/android/provider/Settings.java
	core/java/android/view/VolumePanel.java
	packages/Keyguard/src/com/android/keyguard/KeyguardViewMediator.java