balsam queue submit should indicate if site is down

[tomuram]

Suggestion: It would be helpful if balsam queue submit indicated that the target site was down. It's a common user error to submit jobs and then wonder why Balsam is not submitting them. Something like the following would suffice:

$ balsam queue submit [options]
Note: Site "submitsite" is not active. The site will process these jobs after it has been restarted with balsam site start on the site host.

If we can specify the site host in the message, that would be helpful to the user.