RHEVM3, OpenStack -- Include SSG logo into generated HTML guide if system oscap version supports it

Same change like in:
  [1] https://github.com/OpenSCAP/scap-security-guide/commit/264823961270a1cb47643a5dbfb8870921543443

but this time for RHEVM3 & OpenStack products. Besides that the change updates initial content of the <front-matter> element present guide.xml (of that product) to match the form it has in RHEL/{6,7} -- IOW add the FedoraHosted URL.

Please review.

Thanks, Jan.