Fixing #34, adding new TURN format for M28

https://webrtc-experiment.appspot.com/chat-hangout/
https://webrtc-experiment.appspot.com/file-hangout/

Both experiments are now firing "channel.onclose" event.

New TURN format is added for RTCMultiConnection v1.1, v1.2 and v1.3 —
DataChannel.js —  RTCall.js — and RTCPeerConnection v1.5 and v1.6