Bastion support for SSH transport

[jamtur01]

The SSH transport should support bastion or jump hosts. A lot of folks run their hosts, especially in AWS/GCP, behind bastion or jump hosts. Without this support it's hard for downstream tools like InSpec to run tests.

[thiagonache]

It's important to be able to configure bastion without use ssh_config workaround for automated tests use cases.

[aaronlippold]

@arlimus @chris-rock This will be a key support feature for many of your government users.

[darksheer]

Any update on this as it's blocking a commonly used deployment paths in CSP's such as AWS VPC private networks?

[clintoncwolfe]

I believe this was fixed by #310 - please re-open if not, thanks!