(2/2) Settings: allow to configure the long press back kill delay

Change-Id: I1aeb40351e2ec2ab6f88df51ae33d8bc4ed87275
Signed-off-by: Chet Kener <Cl3Kener@gmail.com>

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