Update Python client for ZMQ API change.
Update Python client for ZMQ API change.

This automatically returns the singleton IOLoop instance, as in the
pyzmq-14.0.1 ZMQStream implementation.

prevents:

  TypeError: __new__() takes exactly 1 argument (2 given)

Change-Id: I901bb22569059e35c02fd08fc77832075cff44a9

OpenChemistry/molequeue,OpenChemistry/molequeue,OpenChemistry/molequeue