Immersive mode on quick settings based on PA commits

This adds the ability to toggle statusbar / navbar via quicksettings (former expanded desktop), but
using the new 4.4 APIs that allow a swipe-up, swipe-down gesture, to restore bars.

Credits to CM project for the implementation
http://review.cyanogenmod.org/#/c/53468/

Drawables by Arz Bhati

Token from PA

Change-Id: I62f782b7f64c8d320a2364dbff2fdb2dfe617f69

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/res/values/graviton_strings.xml