[SimlarService] now has static boolean mRunning
[CallActivity] make sure finish delayed is only called once
[SimlarServiceCommunicator] now unregisters when service finishes
[MainActivity] now starts other activities if service is running
[SimlarService] fixed bug when going down with no connected activity
[SimlarService] make sure we register MainActivity if terminateCall is invoked
[SimlarService] make sure we register RingingActivity before starting it