SystemUI: Add double tap to sleep gesture

Change-Id: I4c54718e8ec8774677d13917b3a7ffa3b4b18cb5

Conflicts:
	core/res/res/values/config.xml
	core/res/res/values/slim_symbols.xml
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java