Remove mox from test-requirements.txt
Remove mox from test-requirements.txt

mox is a test requirement, but isn't being used. mock was recently named
the chosen mocking library, and it's already in use here in
marconiclient.

Change-Id: I24a73d57ad0ccac29db317e0f4e72efdeb8962d8

openstack/python-zaqarclient