Status bar brightness control

+ added some fixes to original implementation (thanks mostly cm for that)
+ add multiuser support

Change-Id: I108086b07dea9cc6d59bfbdd9652b3aa33dcfe74
Signed-off-by: Kristofer Ard <kristoferard@gmail.com>

Conflicts:
	res/values/aospx_strings.xml
	res/xml/status_bar_settings.xml