proxy missing events from client request to returned stream

A bunch of of events are missing from being emitted in the returned stream, `socket`, `connect`, `upgrade`, `continue`.

http://nodejs.org/api/http.html#http_event_socket

I'm only really interested in the `socket` event so I can use `socket.emit('agentRemove')` on it instead of having to increase the max sockets.

I'm aware I can also listen for the `request` event, which I can then listen to all of these events on. Wanted to know what you thought of this API design.

Thanks for an awesome library. :)