Add a proxier that does what the bouncer does, but proxies requests instead of bouncing them.

The current bouncer tests are more end-to-end tests. We should keep these but also add tests for the individual bouncer request handler methods.

See #1 for the initial bouncer work.
From http://cyclone.io/documentation/web.html#cyclone.web.RequestHandler

> If you want to support more methods than the standard GET/HEAD/POST, you should override the class variable SUPPORTED_METHODS in your RequestHandler class.