fix(client): remove config requirement for Connect

[daboross]

Remove requirement when calling client::Config::connector() that the connector implements Connect.

Removing this requirement allows users to set the connector back to UseDefaultConnector. Previously,
this was not possible.

I'm not sure if there's any specific reason for requiring Connect on this method, as far as I can tell from past commits it was just an included part in the original design?

My use case for this is setting the connector back to UseDefaultConnector, as well as opening up the possibility for a UseHttpsConnector or a similar marker type to be used in a wrapper builder around Config.

Tests fail, but as far as I can tell this is only because of deprecated things that hyper is using. Locally, if #![deny(warnings)] is temporarily commented out, all tests pass.

• The commit messages match the guidelines in https://github.com/hyperium/hyper/blob/master/CONTRIBUTING.md#git-commit-guidelines

[seanmonstar]

Hm, I suppose it's just there to help you catch if you pass something that isn't a Connect, but with this change, you'll still see such an error when you go to build(), so this seems fine!

Let me look into these build errors...

[daboross]

Thanks!

The build errors just seem to be mostly some renames that futures did, would you mind if I just submitted another PR changing those in hyper?

[seanmonstar]

Fantastic, thanks for this and the deprecation fixes!

[daboross]

No problem, thank you!