Websockets + Google Authorization

[watawada]

Issue #28

• Modified passport file and user schema to save user's ID token once authenticated.
• Added get-token route in auth.ts to send user's ID token.
• In bin/www.ts, added socket middleware to verify the user's ID token using the OAuth2 client. If the user is properly authenticated with a valid token, then save the user's user_id in the socket object, which I've extended to have a user field, and call next to listen to the socket server.
• In socket.ts on the client side, added a get token function to retrieve user's token from the backend. If the response to retrieve the token fails (user is not authenticated through Google), then redirect to login page. Added createSocket function that creates the socket server with an 'auth' header for the ID token. If the get token function threw an error, then the createSocket function will not create the server.
• In messages page, modified code to use the createSocket function to create the socket.