(#17083) Add rhev & ovirt support to the virtual fact

Without this patch the virtual fact does not return specific values for
the RHEV hypervisor or oVirt nodes.  This path addresses the problem by
implementing specific checks for these virtualization platforms.
Merge branch 'jaredcurtis-ticket/1.7.x/17083_virtual_support_for_RHEL_oVirt' into 1.7.x

* jaredcurtis-ticket/1.7.x/17083_virtual_support_for_RHEL_oVirt:
  (#17083) Add rhev & ovirt support to the virtual fact

closes #397