Add the ability to route requests based on request method.

[trq]

Currently routing completely ignores the request type when mapping a route to a controller. We could gain much finer grained control over route mapping by allowing the request type to play a part in this process.

This would mean the a url such as /foo could map to two completely different controllers depending on wether or not it is GET or POST.

[trq]

Part of implementing this should also be changing the Router (and likely Routes) to accept the Request object. This is something that should be implemented anyway as it opens the door to different Route implementations based on sub domains etc etc.