Disable keep alives to not keep dead connections

[karelbilek]

Fixes #1035

[orlangure]

Hey @karelbilek and thanks for working on this.

I'm not sure this will work with every possible configuration of remote docker, custom socket names and all that. It might, but I don't have a deep enough understanding of that to make sure it will always work.

Your second idea in the attached issue was to call Close on the client. I think it's a much safer and better option. There aren't many places that create a new client, so adding a simple defer shouldn't be an issue. What do you think?

[karelbilek]

Closed in favor of #1041