Peer connect and event websocket connection hooks.

[AdamMagaluk]

Implements #314

.use(function() {
  // Peer connection
  server.httpServer.onPeerConnect(function(request, socket, head, next) {
    // Handle auth logic, 
    next(); // Continue the peering process
    // or
    next(new Error('Some error')); // Response to peer will be 500
  })

  // Regular data websocket connections
  server.httpServer.onEventWebsocketConnect(function(request, socket, head, next) {
    // Handle auth logic, 
    next(); // Continue the event_socket process
    // or
    next(new Error('Some error')); // Response to client will be 500
  })
})

It also allows for multiple hooks for each event by calling the method more than once. In that case each hook is called in series.

[mdobson]

+1