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.

.travis.yml

@@ -9,10 +9,6 @@ matrix:
         - rust: beta
         - rust: stable
           env: HYPER_DOCS=1
-        - rust: stable
-          env: FEATURES="--no-default-features"
-        - rust: stable
-          env: FEATURES="--features compat"
         - rust: 1.21.0
 
 cache: