By testing with data from various schema versions, we effectively check
that they are equivalent.
Also this uncovered a few places where we were not strictly ordering
things - add some sorts in there.
* Zones are now subnets
* Utility subnet is no longer part of Zone
* Bastion InstanceGroup type added instead
* Etcd clusters defined in terms of InstanceGroups, not zones
* AdminAccess split into SSHAccess & APIAccess
* Dropped unused Multizone flag