Fix unlocked account check on Ansible 2.2
Fix unlocked account check on Ansible 2.2

The unlocked account check for V-34896 always fails in Ansible 2.2,
even when there are no unlocked accounts on the system. This patch
simplifies the jinja loop and rejects any empty lines.

Closes-bug: 1585349

Change-Id: I11728e24f341ec696da3a761f02087266341cf2a

major/openstack-ansible-security,major/openstack-ansible-security