The tiebreaker is first-come first serve - ie whichever VM had the name
or IP first wins (based on VM id). The sync() method now sorts the VM
list by id in order to evaluate the tiebreaker correctly (VM list comes
that way from ONED but just in case...).
Instead of clearing the live zone and iterating through and adding
records from OpenNebula we build an entirely new zone, sync it with
OpenNebula, and instantaneously swap it with the currently live zone.
This minimizes the amount of time that the DNS server is missing entries
while its syncing with OpenNebula.
Vitaliy Filippov
Justin Riley