This enable cluster_user_trust customization which is needed to get
Kubernetes integration with Cinder and Neutron LBaaS.

https://github.com/openstack/magnum/blob/master/releasenotes/notes/CVE-2016-7404-f53e62a4a40e4d30.yaml#L5

Change-Id: Ib3243b110d2c592f3bf6467b086738335799c853