Add WebRTC wrapper and backend

[anto-christo]

Adds the following features:

• Connect with Name Server to register a Master and setup WebRTC connections.
• Start/Stop a Master to make it available/unavailable for WebRTC connections.
• Connect/Disconnect multiple Clients to a Master using the Master name.
• Authenticate a client.
• Transfer data between Master and Clients.
• Synchronize operations between the Master and Clients via WebRTC backend.
• Connect to a private STUN-TURN server (By default connects to public STUN servers).
• Detailed documentation.

The Name Server (https://github.com/anto-christo/WebRTCNameServer) has been implemented using FrappeJS.