feat(lib): replace types with those from http crate

BREAKING CHANGE: `Method`, `Request`, `Response`, `StatusCode`,
  `Version`, and `Uri` have been replaced with types from the `http`
  crate. The `hyper::header` module is gone for now.

  Removed `Client::get`, since it needed to construct a `Request<B>`
  with an empty body. Just use `Client::request` instead.

  Removed `compat` cargo feature, and `compat` related API.

src/common/mod.rs

@@ -1,6 +1,2 @@
-pub use self::str::ByteStr;
-
-mod str;
-
 #[derive(Debug)]
 pub enum Never {}