Expose a way to listen to proxy events

[RavenHursT]

https://github.com/nodejitsu/node-http-proxy#listening-for-proxy-events

Right now, the module only exposes the thunk wrapper. There's no handle for the consumer of this library to get ahold of the proxy instance so that something like the following can be done:

proxy.on('proxyReq', (err, req, res) => {
  console.log('Outgoing proxy request => ' , req)
}

[ming-codes]

May I ask what is your specific use case?

Proxying is usually done as the last of the middleware chain where you don't need to do anything else.

If the proxy instance are to be exposed, I would imagine you'll want to do things with it that will eventually yield down to the next middleware.

[RavenHursT]

Just wanting to verify (and log) in a production environment the requests that are passing through the proxy. Not to mention, have some introspection into the requests that are being generated by the proxy and the responses that are being sent back through..