protocol messages on to any remotes that have the same UUID as
the cluster. Needs VIA extension to P2P protocol to avoid cycles.
+* `git-annex updatecluster` needs changes to support a distributed cluster.
+ Currently it will remove nodes that are behind another gateway.
+
* Getting a key from a cluster currently always selects the lowest cost
remote, and always the same remote if cost is the same. Should
round-robin amoung remotes, and prefer to avoid using remotes that