Implement WebRTC support

[monicanagent]

Add reliable NAT hole punching/binding capabilities to server code (https://github.com/monicanagent/cypherpoker.js/tree/master/src/server), in order to enable public server/peer node capabilities without the need for manual router updates.

[monicanagent]

This might be a good place to start: https://github.com/freedomjs/freedom-port-control

[monicanagent]

Unfortunately none of the existing NPM libraries and NAT hole punching techniques (NAT-PMP, PCP, uPnP) seem to be effective. However, since Electron includes a fully functional version of Chrome, WebRTC can be leveraged to accomplish this functionality.

In addition to updating the P2P communication functionality of CypherPoker.JS, RPC functions should also be call-able via WebRTC. This will require some sort of dynamic server and message routing capabilities with the following logic:

Initial connect:

• Connect to preferred server using either WebSocket Sessions or WebRTC (desktop server only) using stored connection data
  • Establish inbound server message routing via WebRTC or WSS depending on connection type
  • Begin gathering SDP and standard WSS services announcements, saving them locally for future use (user should be able to choose their initial connection at startup)

On table join:

• Attempt to connect to peer (table creator) via WebRTC and record success or failure
  • On success, add inbound WebRTC message routing
  • On Failure, retain existing inbound WSS message routing

On send-to-peer:

• Check for active WebRTC connection to peer.
  • If available, send message via WebRTC
  • If not available, send message via WebSocket Session

On invoke RPC:

• Check if primary server connection is WSS or WebRTC
  • If WSS, invoke RPC using WSS
  • If WebRTC, invoke RPC using WebRTC

The server will also need to be updated in order to route messages between WebRTC-connected peers and WSS-connected peers.

Most likely there will be additional implementation details to follow.

[monicanagent]

Updated issue title to reflect new direction (re: WebRTC)

[monicanagent]

Implemented in revision 167 (https://github.com/monicanagent/cypherpoker.js/commit/1af643d72bb416c49fdd7dd98f44cd435f2a9ce5).