monkeysphere-host revoke-key should now be capable of publishing the

monkeysphere-host revoke-key should now be capable of publishing the
revocation certificate to the keyservers directly, should the admin
want that.

It can also run without prompting, if MONKEYSPHERE_PROMPT=false.  In
the no-prompts case, it never publishes to the keyserver, it indicates
that the key was compromised, and it writes a boilerplate description
to make it easy to identify this kind of certificate.