unpairing couchdb replication

[Chad Miller]

For replication, we already support pairing, but we must also support un-pairing machines.

For pairing, we require that both machines be present and talking to each other, but we do no want to require that for un-pairing. The trick becomes how to set the offline machine not to replicate to us any longer. Since the replication daemon is already noticing when the remote machine appears on the network, that daemon is the best place to put logic to finish the step of un-pairing, remote from local.

For local records that represent hosts we want to un-pair with, we should add a new attiribute,
'unpaired'=True
to the top level of the record.

For finding pairings, the pairing tool must ignore records that have {'unpaired'=True} set, and for new pairings, must remove any records that have {'unpaired'=True} .

The replication daemon must scan local records when a new host appears on the network, and if the local record has {'unpaired'=True} , then it must connect to the remote management database, remove all records that have the local host id as a pairing target, and then remove the local records that have the remote hostid as a pairing target.