Settings: Add Omni's PerformanceControl

	modified:   Android.mk
	modified:   AndroidManifest.xml
	new file:   res/drawable-hdpi/ic_settings_performance.png
	new file:   res/drawable-mdpi/ic_settings_performance.png
	new file:   res/drawable-xhdpi/ic_settings_performance.png
	new file:   res/drawable-xxhdpi/ic_settings_performance.png
	modified:   res/values/liquid_strings.xml
	modified:   res/xml/dashboard_categories.xml

Change-Id: I3356cc4b2527196a180d65bdc141d6664a6b5ec6