Make certificate_authority policy entries consistent

[Jason Fritcher]

The following entries in policy.json use role: instead of rule: like the surrounding entries. For consistencies sake, these should be changed to use rule:

"certificate_authority:add_to_project": "role:admin"
"certificate_authority:remove_from_project": "role:admin"
"certificate_authority:set_preferred": "role:admin"

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/200766

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/200766
Committed: https://git.openstack.org/cgit/openstack/barbican/commit/?id=93b9bc4a7292ea676b4cc4f119dd187301084a18
Submitter: Jenkins
Branch: master

commit 93b9bc4a7292ea676b4cc4f119dd187301084a18
Author: Jason Fritcher <email address hidden>
Date: Fri Jul 10 16:22:23 2015 -0700

    Fix policy.json certificate_authority inconsistency

    Change the certificate_authority add_to_project, remove_from_project,
    and set_preferred entries to use rule:admin instead of role:admin. This
    brings these entries into consistency with their neighbors.

    Closes-Bug: #1473593
    Change-Id: Ibdb7512cf751b92298e350dac1689b036a6fd023