[2/2] ElectronBeam: Add an alternative screen-off animation

Adds a selector to choose the screen-off animation.

Change-Id: I5109ca899a75dae2e991ca57811acd57af10a48b

Conflicts:
	res/values/custom_strings.xml
	src/com/android/settings/DisplaySettings.java

Conflicts:
	res/values/illusion_strings.xml