settings: Cleanup and add auto power profiles option

 * Add categories for all items
 * Add helper class for Settings.Secure

Change-Id: I9d8fd6720516e7fa321c05744ada81415cbf8aaa
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0-sgt7

Conflicts:
	res/values/cm_strings.xml
	res/xml/performance_settings.xml