Updating rhev events to map to policy events

The HOST_REGISTER_SUCCEEDED rhevm event is never thrown from RHEV from what I
can tell in the rhev logs.  The closest rhevm event is HOST_DETECTED.  This
event is emitted from rhev whenever a host is added.  This rhevm event best
correlates with the CFME "host_connect" policy event.

For the "host_disconnect" CFME policy event, the rhevm event USER_REMOVE_HOST is
the closest match.

https://bugzilla.redhat.com/show_bug.cgi?id=1009432
https://bugzilla.redhat.com/show_bug.cgi?id=1009434