FS: Socket.io setup

[aeciorc]

Add socket support on the front-end and back-end s

• Setup socket server on the backend
• Setup client connection :should connect if the user is authed, add some layer of security would be best.
  • Tip:- Use the sockets handshake *check the .headers.cookies field)
• Add a basic event type that logs a message on the server when a user is connected
• We also want an object to keep track of which users are currently connected - for simplicity, you can for now just use an in-memory variable (like a dictionary or object in the back-end - not recommended for scability, but it works for this project)