A builder for building routes, tied to Hyper’s types and our Handler.
We add some shortcut methods onto this type in order to make building
routes for hyper easier.
The handler that’s stored as a part of every route in the router. Since
we’re dealing with Hyper, it must return a future; we use the Box<Fn>
type in order to keep flexibility.
The router type, tied to Hyper’s types, and our Handler. This
implements [hyper::serivce::Service] by default, and if no default handler
is given, it returns an empty 404 response.