Extend get_users module to get groups
Extend get_users module to get groups

The get_users module also needs to get group data. This patch adds that
functionality and refactors the module a bit. This is required for
RHEL-07-02300.

Change-Id: Idd57ca197ad69641de7b729e4d75f50d953ea117

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