Update Rakefile
Merge branch 'master' into 38257-Move-thread-from-TDReplicatorManager-to-TDReplicator
Adds access to and tests of the TDReplicator NSThread object.

Can access the TDReplicator's replicator thread's execution state.
Also exposed in CDTReplicator.

Adds to tests that examine the replicator thread's execution state
which verify the thread exits and cancels appropriately.