Allow changing screen-off animation (2/2)

* Allow enabling/disabling screen-off animation
* Allow selection between fade & crt effects if the device allows it

Change-Id: I5ebfab22e68ea34e3babfaacd9c8103e25932d3d

Conflicts:
	res/values/cm_arrays.xml
	res/values/cm_strings.xml
	res/xml/display_settings.xml
	src/com/android/settings/DisplaySettings.java