Make heartmonitor.Heart monitorable
Make heartmonitor.Heart monitorable

If a mon_addr is given, send any ping to this zmq socket. This can be
used to monitor the heartbeat on the engine side to check if the cluster
controller is still active.

Also correct the code on __main__ to work (for testing purpose).

Signed-off-by: Jan Schulz <7fb630b19ed7bf3033a3f003af589997c9df045d@gmx.net>

ipython/ipython,ipython/ipython