Adding oVirt verbs related to host's api

Those verbs are used by ovirt-provision-plugin which introduced as part of feature [1]

[1] http://www.ovirt.org/Features/AdvancedForemanIntegration 
please make sure that if empty cluster is passed, there's a proper err handling on oVirt side, or make sure not to pass an empty cluster to oVirt side and exclude it from the request.