Add System menu and PowerWidget configuration support from mr0/10.0

Change-Id: I4c34812be0bc39dbe93e21a29682717ccf9c077f

Conflicts:
	res/drawable-hdpi/ic_settings_system.png
	res/drawable-mdpi/ic_settings_system.png
	res/drawable-xhdpi/ic_settings_system.png
	res/values/config.xml
	res/values/strings.xml
	res/xml/settings_headers.xml
	res/xml/system_settings.xml
	src/com/android/settings/cyanogenmod/SystemSettings.java