Bug 877077 - Pass the call node to keypad manager when updating

https://bugzilla.mozilla.org/show_bug.cgi?id=877077

When initializing the handled call of the second incoming call, CallScreen.activeCall is still the node the first call. Which results to that the additional information of the node representing the first call is altered with the information of the second call.

In this patch we pass the call node to the update function explicitly. In addition to it, remove the 'resumed' case (which is not existing) and fix the CallScreen.activeCall function.