feat(status): add StatusCode::try_from(u16).

This is a temporary function until the `TryFrom` trait stabilizes.

BREAKING CHANGE: Removes the undocumented `from_u16` function. Use
  `StatusCode::try_from` instead.

  Also makes the `status` module private. All imports of
  `hyper::status::StatusCode` should be `hyper::StatusCode`.

src/lib.rs

@@ -57,6 +57,6 @@ mod method;
 pub mod header;
 mod http;
 pub mod server;
-pub mod status;
+mod status;
 mod uri;
 mod version;