[2/3] QuickBoot: enable QuickBoot Settings UI

Add QuickBoot enable item in DevelopmentSettings.

Change-Id: Id2aaec4ad3e85f51235db4c25d49136a26502e20

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

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