SystemUI: Immersive Mode toggle

Change-Id: Ic818f3f92d143c203bf99fb43198152942a186dc
Signed-off-by: Brandon McAnsh <brandon.mcansh@gmail.com>

Conflicts:

	packages/SystemUI/res/values/strings_toggles.xml
	packages/SystemUI/src/com/android/systemui/statusbar/toggles/ToggleManager.java