Need to persist vbucket state

See MB-1290. If a node with active vbuckets goes down and any of those vbuckets don't have data, the janitor has no idea what to do with it when it comes back because the janitor doesn't know it didn't have data, but it sees only a replica node. If the replica had data, creating a new vbucket on the master would destroy the replica.

Need to have any vbucket that was in active state come up in pending state when the node restarts, regardless of whether it had data in it.