Remove test_create_port_with_no_ip

The check test_create_port_with_no_ip does can be performed by adding
self.assertEqual(port['fixed_ips'], []) to test_show_port.

Plus, amended docstrings.

Change-Id: I31e31657ab18ec22d4f2c66b1d34f8762ab99daf
Merge "Remove test_create_port_with_no_ip"