Include the creation of server too. Previously, the parameter type of
the closure had a different type than the default server provided, which
wasn't obvious to the user.
This adjusts the way `Service`s are created for a `hyper::Server`. The
`MakeService` trait allows receiving an argument when creating a
`Service`. The implementation for `hyper::Server` expects to pass a
reference to the accepted transport (so, `&Incoming::Item`). The user
can inspect the transport before making a `Service`.
In practice, this allows for things like getting the remote socket
address, or the TLS certification, or similar.
To prevent a breaking change, there is a blanket implementation of
`MakeService` for any `NewService`. Besides implementing `MakeService`
directly, there is also added `hyper::service::make_service_fn`.
Closes#1650
