Fixes 'groups' flag func. of workspace node-list
Fixes 'groups' flag func. of workspace node-list

https://github.com/redhat-openstack/infrared/issues/311

RHOSINFRA-1625

Change-Id: I60aa90129cc5ab64a7f011d43fa84680e91d17e8

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared