Summary of changes:
* Request no longer has a lifetime parameter.
* Handler type now includes a `Data` parameter.
* Response is now an enum that is either `Complete` or `Forward`.
* Outcome enum is now one of: Success, Failure, Forward.
* Outcome::Foward for Responses must include StatusCode.
* Responders are now final: they cannot forward to requests. (!!)
* Responsers may only forward to catchers. (!!)
* Response no longer provides wrapping methods.
* Route is now cloneable.
This change is fundamental to enabling streaming requests.
This means we have almost all of the infrastructure in place to properly use
ranked requests. At the moment, we only use this to allow user error handlers
when a responder fails. But, soon enough, we'll try the next highest ranked
route until there are no more matching routes. Yipee!
Here's the idea: under the `Rocket` namespace should live things critical to
writing simple Rocket apps: Request, Response, Error, etc. Nothing should be
nested more than one level deep. Only items required for more complex things
(implementing uncommon traits, etc.) should be nested one level deep.
This commit is the first attempt at realizing this.
There's something going on with Hyper. When a 303 (see other) response is sent
in response to a POST, the browser does a GET to the location header. Hyper
somehow misreads the method parameter here, resulting in a route failer.
I need to MITM the connection to see exactly what the browser is sending and
what Hyper is receiving to see who's wrong.
Okay, so, given a URI, we can figure out which route is corresponds to.
Unfortunately, the handler is not yet part of that route, and we're not parsing
the parameters from the path quite yet. But, we're almost there!
