Delete policy.json from repo since we can use policies registered
in code.
We can also change default policy rules through below steps:
- generate policy.yaml and copy to /etc/barbican
- configure `policy_file=policy.yaml` in `oslo_policy` section
- uncomment rules in policy.yaml and make changes as we desire
- restart barbican api service
- test whether new rules take effect on corresponding API
Change-Id: Ia64eac1eb4e30457b323c6ab99d26d3d40c28060
73420137a6