Telephony:  Add transparency to Glowpad background [3/3]

Adds the option to make glowpad view background transparent on incoming call so the caller's entire picture can be seen.

Change-Id: I85cf0ff99fa7536275f7b1928d554e1b7ab68b3e

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