[1/2] SystemUI: Add brightness slider to notification drawer

adds a brightness slider below the expanded statusbar header and
(if enabled) quick settings ribbons

also wrap an if around gesture recorder in the fling methods, only
call them if DEBUG is enabled.

Change-Id: I65077f5ddb20aa9f13813eedfaa0cb09a667eb88

Conflicts:

	core/java/android/provider/Settings.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java