This also allows us to remove our `hyper` dependency.

Turns out we were just using the re-export of the `percent-encoding`
trait anyways. The `Url` type comes from `reqwest`.

This release fixes an issue that occurred frequently with Gitlab
communication.

See https://github.com/hyperium/hyper/issues/1396 for details.

This reverts MR !61. Now that reqwest 0.7 detects whether the client has
timed out or not, we only fail when the connection is lost between
checking the status of the client and the communication itself.

See https://github.com/seanmonstar/reqwest/issues/44.

This reverts commit 35b07e59, reversing
changes made to b9c20ea2.

The chrono 0.3.1 release was yanked from crates.io due to breaking
semantic versioning (chrono issue 156).  Now chrono 0.4 has been
released to support serde 1.0.