Telephony: Heads up meets SlimKat....SlimKat meets Google IO [3/4]

Add heads up setting for the native integration in dialer

Enabled by default

PS
- derp

PS
update commit message header

Change-Id: I3bf763ba2e8989933a5e024ee3dd7e030bc34f5b

Conflicts:
	res/values/slim_strings.xml
	res/xml/call_feature_setting.xml
	src/com/android/phone/CallFeaturesSetting.java