webrt: set the localStream
webrtc: set the remoteStream
CallView: first draft
CallView: implement the _displayLocalVideo handler
WebRTCCall: refactor _getMedia to be more readable
Make _getMedia attach the localStream to its PeerConnection; mostly paired with @tOkeshu
Fix issues surfaced by jshint
Merge branch 'chatapp-webrtc'.  This adds _getMedia support to WebRTCModel, cleans up some tests, and checkpoints the chat CallView.  r=@Standard8