Add start() method back to Replicator interface since the semantics of Subscribers returned by that interface do not make sense unless the caller can controller when the Subscribers begin issuing notices. Then, change ReplicatorService not to call start() itself, since its user needs to be free to subscribe to a newly created Replicator before starting it.
Lambda replacement in ReplicatorService
Add method getCommittedEntryChannel to Replicator interface, and stub it out in implementing classes. This method will be used to implement c5#283