Settings: Allow choice of screen-off animation (2/2)

Adds a choice of alternative screen-off animations:

- Fade out
- Electron beam (default)
- Scale down

Change-Id: I50e7c1d5989cc6004cf635af11e0f775cdd21f0c
Conflicts:
	res/values/pa_arrays.xml
	res/values/pa_strings.xml
	src/com/android/settings/DisplaySettings.java