framework: Add compass tile (1/2)

Add a compass tile to quick settings.
Clicking on it enables the sensor and clicking again disables it.

Screenshot: http://goo.gl/2frdpy

Change-Id: Icd9d12929f0491f6958f30de139ef39bb4c2e037

Conflicts:
	core/java/com/android/internal/util/slim/QSUtils.java
	packages/SystemUI/res/drawable/btn_ga_cancel_gesturing.xml
	packages/SystemUI/res/values/slim_strings.xml
	packages/SystemUI/src/com/android/systemui/statusbar/phone/QuickSettingsController.java