Add test for 'port-show --field' command
Add test for 'port-show --field' command

Change-Id: Ib8e94a84ef9b4b171b7d1c20f36f16301d244588
Closes-Bug: #1568755

NaohiroTamura/python-ironicclient,openstack/python-ironicclient,NaohiroTamura/python-ironicclient,openstack/python-ironicclient