[wip] 070-couch-db.t
[squash] clustered changes support
[squash] 071-couchdb-rapid-cycle.t
[squash] 072-cleanup.t
[squash] 073-changes.t

This changed a lot cause of how Db's behave now in that you have to call
reopen to access records you've written. Ie, if you write a doc, and
then try and write a new revision without reopening you'll get a
conflict because the prepare_and_valdiate_* side is using old #btree{}
states that don't have the proper snapshot to extend the previous
revision.