Button & keyboard backlight brightness adjustment (1/2)

PS2: move from display to button settings
PS3: fix tab

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: I35a6d149affc1da08707b7c40fb02761321cba41

Conflicts:
	res/values/cm_strings.xml
	res/xml/hardware_keys.xml
	src/com/android/settings/cyanogenmod/BootReceiver.java
	src/com/android/settings/cyanogenmod/HardwareKeys.java