Bugs fixed: DataChannel.js and RTCMultiConnection.js

https://webrtc-experiment.appspot.com/#DataChannel
https://webrtc-experiment.appspot.com/#RTCMultiConnection

It was a bug which is fixed now. Two unique sessions was opened for
initiator.

1) First session was playing role of participant --- this session is
auto opened
2) Second was playing role of initiator --- this session is manually
opened by the user

Now, RTCMultiConnection-v1.2.js only opens one-session all the time.
Test it:
https://webrtc-experiment.appspot.com/RTCMultiConnection/users-ejection/