Fixes bug #122. Add a call to close to the message test to exercise the code. Verified the test fails without the fix.
…ns and stops all PeriodicCallbacks. To close those callbacks, the _run() method needed to be updated so that we could keep track of them.
This fixes an issue where when in backoff on requeue with backoff=False the reader would stall and would not send any more RDY count.