refactor(http): merge Request and Response from server and client

Request and Response are now visible from:
- hyper::{Request, Response}
- hyper::server::{Request, Response}
- hyper::client::{Request, Response}
They truly exist in the http module, but are re-exported to reduce the number of breaking changes.

request::new and response::new were renamed to ::from_wire to reduce confusion with Request::new
and Response::new. See issue #1126

Request now has an optional Body, because not all requests have bodies.
Use body_ref() to determine if a body exists.
Use body() to take the body, or construct one if no body exists.

Closes #1155

BREAKING CHANGE: Response::body() now consumes the response

tests/server.rs

@@ -503,7 +503,7 @@ fn test_server_disable_keep_alive() {
         .status(hyper::Ok)
         .header(hyper::header::ContentLength(quux.len() as u64))
         .body(quux);
-    
+
     let _ = req.write_all(b"\
         GET /quux HTTP/1.1\r\n\
         Host: example.domain\r\n\
@@ -522,4 +522,4 @@ fn test_server_disable_keep_alive() {
             panic!("read {} bytes on a disabled keep-alive socket", n);
         }
     }
-}
+}