Immersive mode on quick settings

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 Bhatia

Patchset 2: Rebase
Patchset 3: No change, was never supposed to happen....

Change-Id: I1f694d87f0364aed7b6951714ea2bfbfd8555064

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