Cleanup UI and stop Firebase listeners on user sign-out
Cleanup UI and stop Firebase listeners on user sign-out

Change-Id: Ib7db0129dcde1bb10d6bf527931cfc9e8ef8a9d6

jmarantz/soccersub,uhntiss/quickstart-js,robforee/YA,DES157/quickstart-js,firebase/quickstart-js,yochannah/trafficuk,firebase/quickstart-js,yochannah/trafficuk,DaryaBeda/firebase_,uhntiss/quickstart-js,jmarantz/soccersub,uhntiss/quickstart-js,DaryaBeda/firebase_,theGove/atlas,robforee/YA,DES157/quickstart-js,theGove/atlas,robforee/YA,jmarantz/soccersub,firebase/quickstart-js