Remove unused socket.io cookie

The socket.io cookie doesn't really have any purpose as it's no longer
user in modern socket.io versions. This patch disables it.

References:
https://github.com/socketio/socket.io/issues/2276
Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

app.js

@@ -57,7 +57,7 @@ app.use(morgan('combined', {
 }))
 
 // socket io
-var io = require('socket.io')(server)
+var io = require('socket.io')(server, {cookie: false})
 io.engine.ws = new (require('ws').Server)({
   noServer: true,
   perMessageDeflate: false