Extend fencing to hosts using fence_rhevm agent.
Extend fencing to hosts using fence_rhevm agent.

This commit extends the fencing class allowing operators to use
fence_rhevm for nodes running on oVirt / RHV.

Change-Id: I1499ef2efce2b5708262d587bf5786a329e10b09

openstack/puppet-tripleo,openstack/puppet-tripleo,openstack/puppet-tripleo