Add more explanation in case of disable heads up through master switch

- Call ui and mms will stop receive heads up notifications automatically

Change-Id: Ie800b84e203d59cb922b82815f538cc28ec1c8e6
Settings: Heads Up background color && transparency [1/2]

Change-Id: I7a37f9d5a7c0e682b1f9670c3b839e3f063dc45c
PS12: squash dependency - heads up settings now under interface menu
PS: add ability to set custom heads up text color

Conflicts:
	res/values/cr_strings.xml