Heads up: option to disable in lockscreen (1/2)

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java

Change-Id: I919a129cd20bc18e85141a10cbd3eb7befc9edd1
Merge remote-tracking branch 'carbon/kk' into kk