Add option to pass through properties and option to avoid sending response

Ended up making a number of changes and implementing them so they won't break your existing stuff. I don't have ant installed on this computer so couldn't run tests, but wrote a theoretically working test for the new stuff.

This allows your to pass some properties to your base React component through from the server. I am using this to pass the port and url the server starts on. This keeps you from having to use the [full url](https://github.com/andreypopp/react-quickstart/blob/master/client.js#L33).

The sendResponse option lets you chain the middleware if you'd like. This lets me (add the <!doctype> here)[https://github.com/natew/reactor/blob/master/app/server.js#L36].

You can see the full usage [in reactor](https://github.com/natew/reactor/blob/master/app/server.js#L33) (url passing not yet working, still need to figure out some stuff there).