WP-CLI-over-SSH should have timeout support

[paulgibbs]

Expected behaviour

When Wordhat runs a WP-CLI command over SSH, if the remote host is unreachable, then the request should time out quickly, and display an appropriate error message.

Current behaviour

At least one of my projects, it just sits there. Seemingly forever.

Possible solution

Not obligatory, but you can suggest a fix/reason for the bug. Thanks!

Steps to reproduce

Provide a link to a live example, or an unambiguous set of steps to reproduce this bug. Include code to reproduce, if relevant.

1. Set up a Chassis project.
2. Modify wp-cli.yml "host = [email protected]"
3. Run a Behat test against a feature file.

Context

I noticed it when I started to code without enough tea.