Changes the CDTReplicator.state property to be equal to CDTReplicatorSta...


If the replication was stopped via a call to CDTReplicator -stop, the status should be 'Stopped'. Otherwise, if
the replication stops on its own because it completes, the status is set to CDTReplicatorStatusComplete.

Changes the CDTReplicator code to clarify the object's state,
progress (changesTotal and changesProcessed), and messages sent to delegates
during start, stop and updates to the replicator.

Adds tests in ReplicationAcceptance using a delegate to stop replication
immediately after starting.
Brace formatting on all your changes to if statements needs checking ([style guide](https://github.com/cloudant/CDTDatastore/blob/master/doc/style-guide.md#conditionals-and-loops)].