fix for pyzmq 13.x 'Socket has no such option: _EVENTLET_SEND_EVENT' errors

attempted to use eventlet with pyzmq 13.x but encountered `Socket has no such option: _EVENTLET_SEND_EVENT` errors instantiating socket objects.

these changes remove those errors and allow the tests in `zmq_test.py` to pass and seem from initial tests to work fine so pushing them here for review / comment.