add creating WebSocket server from scratch, using only the RFC doc

[AhanShankar]

Adding building WebSocket server from scratch, using only the RFC documents. I know that there is already a WebSocket tutorial, but this adds value for the following reasons:

1. Its in JS, while the existing tutorial is in Ruby
2. Follows the RFC doc much more closely, providing references
3. A lot more elaborate, with diagrams and references
4. Supports closing hanshakes, ping and pong frames, which the current tutorial does not