Base: Option to enable Notification Light when screen is on [1/2]

This makes it possible to let the Notification LED flash even when the screen is on
[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.
Over scroll effects [1/2]

Change-Id: I4cc67715f8f3bc67674782f08b9e363ee0e8ac9e