reqwest 0.7.0 on Rust Cargo

Features

Proxy support (#30)
Self-signed TLS certificates (#97)
Disabling TLS hostname validation ⚠️ (#89)
A Request type that can be used instead of the RequestBuilder (#85)
Add Response::error_for_status() to easily convert 400 and 500 status responses into an Error (#98)
Upgrade hyper to 0.11
- Synchronous Client remains.
- Timeouts now affect DNS and socket connection.
- Pool much better at evicting sockets when they die.
- An unstable Cargo feature to enable reqwest::unstable::async.
A huge docs improvement!

hyper has been upgraded to 0.11, so header, StatusCode, and Method have breaking changes.
mime has been ugpraded to 0.3, with a very different API.
All configuration methods have been removed from the Client, and moved to the ClientBuilder.
The HttpVersion type was completely removed.
Error::cause() now returns Error::get_ref().cause().
All methods on Client that start a RequestBuilder now return a Result immediately, instead of delaying the URL parse error for later.
The RequestBuilder methods all take &mut self, instead of moving the builder, and return &mut Self. (This shouldn't actually affect most people who are building a request in a single chain.)
Response::status() returns a StatusCode instead of &StatusCode.