Status bar brightness control

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

Change-Id: I4d9c68ec7d1b434826960f75ad38d9ecc3434b12

Conflicts:
	res/values/bs_strings.xml

Conflicts:
	res/values/blk_strings.xml
	res/xml/status_bar_settings.xml
	src/com/android/settings/blackout/StatusBar.java