Quiet Hours: Clean up and consolidate code

- Added: Allow disabling of system sounds

Ported from cm-10.2.

Change-Id: I7d2619becb99c336d23896a672136f491d972abd

Conflicts:
	core/java/android/provider/Settings.java
	services/java/com/android/server/BatteryService.java
	services/java/com/android/server/NotificationManagerService.java
	services/java/com/android/server/VibratorService.java