Add pyzmq to requirements.txt

[Oleksii Zamiatin]

Lack of the python-zmq library reference in requirements causes import error.

This line supposed to be a fix
https://github.com/openstack-dev/devstack/blob/master/lib/rpc_backend#L169

but still have:

2015-02-05 14:48:52.805 | Traceback (most recent call last):
2015-02-05 14:48:52.805 | File "/usr/local/bin/nova-manage", line 9, in <module>
2015-02-05 14:48:52.805 | load_entry_point('nova==2015.1.dev825', 'console_scripts', 'nova-manage')()
2015-02-05 14:48:52.805 | File "/opt/stack/nova/nova/cmd/manage.py", line 1306, in main
2015-02-05 14:48:52.805 | config.parse_args(sys.argv)
2015-02-05 14:48:52.805 | File "/opt/stack/nova/nova/config.py", line 56, in parse_args
2015-02-05 14:48:52.805 | rpc.init(CONF)
2015-02-05 14:48:52.805 | File "/opt/stack/nova/nova/rpc.py", line 63, in init
2015-02-05 14:48:52.806 | aliases=TRANSPORT_ALIASES)
2015-02-05 14:48:52.806 | File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/transport.py", line 186, in get_transport
2015-02-05 14:48:52.806 | invoke_kwds=kwargs)
2015-02-05 14:48:52.806 | File "/usr/local/lib/python2.7/dist-packages/stevedore/driver.py", line 45, in __init__
2015-02-05 14:48:52.806 | verify_requirements=verify_requirements,
2015-02-05 14:48:52.806 | File "/usr/local/lib/python2.7/dist-packages/stevedore/named.py", line 55, in __init__
2015-02-05 14:48:52.806 | verify_requirements)
2015-02-05 14:48:52.806 | File "/usr/local/lib/python2.7/dist-packages/stevedore/extension.py", line 170, in _load_plugins
2015-02-05 14:48:52.806 | self._on_load_failure_callback(self, ep, err)
2015-02-05 14:48:52.807 | File "/usr/local/lib/python2.7/dist-packages/stevedore/driver.py", line 50, in _default_on_load_failure
2015-02-05 14:48:52.807 | raise err
2015-02-05 14:48:52.807 | ImportError: Failed to import eventlet.green.zmq
2015-02-05 14:48:52.838 | + exit_trap

with devstack.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/152966

[OpenStack Infra (hudson-openstack)]

Change abandoned by Oleksii Zamiatin (<email address hidden>) on branch: master
Review: https://review.openstack.org/152966
Reason: These packages are optional, so they are to live in test-requirements.

[Oleksii Zamiatin (ozamiatin)]

Pip freeze output shows that package wasn't installed.