Settings: Forward port Kill app back long press

Original author: DaneshM

PatchSet2
- rebased

Patchset3
- cleanup whitespaces

Change-Id: I5e9ae7da762615722ce9dc09c4b7053b77736a62

Conflicts:
	res/values/strings.xml
	res/xml/development_prefs.xml
	src/com/android/settings/DevelopmentSettings.java