This seems like a good place to ask: Does anyone know of a library (preferably C++/Emscripten) that simplifies using WebRTC to create real time network games?
I looked for a library for a similar WebRTC project. All of the libraries I found contained superfluous functionality, as I was only interested in data channels and did not want to be locked in by a particular third party. I ended up rolling my own; the WebRTC API is simple enough [1] and there is some example code from Google that points the right direction [2]. Additionally, Socket.io makes for a convenient signalling server prototype, though it is overkill.
If you want a simpler signaling server for WebRTC, you might check out the "caress" server I developed for Chatphrase: http://github.com/chatphrase/caress
[1] http://dev.w3.org/2011/webrtc/editor/webrtc.html
[2] https://bitbucket.org/webrtc/codelab