Ticket/2.x/17083 virtual support for rhel ovirt

This commit adds support for identifying RHEV and oVirt as virtual platforms.

Reference Ticket 17083 for details,https://projects.puppetlabs.com/issues/17083

I based this off of the 2.x branch, which is what the guidelines suggested but it appears that branch is not available to merge into, so I picked 1.7.x. Hopefully this doesn't cause too much of a headache when merging. If needed I can redo the commits off a 1.7.x branch.