[1/2] Configureable Pulldown Notification for QuickSettings

PS1:fixed a typo in SettingsObserver
[1/2] Base: Disable safe headset volume warning

Settings: https://gerrit.omnirom.org/#/c/5203/

PS7
adjust defaut value

Change-Id: I83e2f180a872ccdec99ef44c4455f6173da340cc

Conflicts:
	core/java/android/provider/Settings.java
	media/java/android/media/AudioService.java