Allow the use of checkpoint to be optional

A new parameter use_checkpoints which defaults to be true can be either used in the replicator section of
ini files and/or used in the replication command or doc added to the replicator db. When this option is set
to false no checkpoints are taken. It should be used with caution and only for small dbs.

BugzID:14327
Monitor spawned calls to fabric

When continuous replications crash, a race condition prevents the replication doc from
being updated to reflect the error status. Monitoring the spawned calls to fabric update
prevents this.

BugzID: 17134
Scope entries to their replicator db