Settings: Add HeadsUp setting.

Change-Id: Ib7a59145843bedb16aacc87bf6d3c6da143e8d3e

Conflicts:
	res/values/cm_strings.xml
	res/xml/notification_drawer.xml
Settings: Add heads up blacklist options. (2/2)

Change-Id: I13d849b49bee6f516b591625c2ea2e69dff12885

Conflicts:
	AndroidManifest.xml
	res/values/cm_strings.xml
	res/xml/notification_drawer.xml
	src/com/android/settings/cyanogenmod/NotificationDrawer.java