Async (hyper 0.11)

[theduke]

Since hyper 0.11 has been released,
can a switch to 0.11 go ahead already?

Like mentioned elsewhere, a SyncClient plus an AsyncClient would be neat.

If can lend a hand.

[seanmonstar]

Yes, work can start. Since an async client necessitates use of the Future trait, and that won't stabilize before reqwest 1.0, an exposed async Client would need to be in a separate crate.

However, there is benefit in using this async crate inside the sync one, as it does a better job of detecting dead sockets and allowing connect/dns timeouts, and make use of the new headers and mime updates.

[seanmonstar]

Ah, this was done in #151.

[theduke]

Awesome!