With the new config option `keystone_auth_default_policy`, cloud admin
can set a default keystone auth policy for k8s cluster when the
keystone auth is enabled. As a result, user can use their current
keystone user to access k8s cluster as long as they're assigned
correct roles, and they will get the pre-defined permissions
set by the cloud provider.
The default policy now is based on the v2 format recently introduced
in k8s-keystone-auth which is getting more useful now. For example,
in v1 it doesn't support a policy for user to access resources from
all namespaces but kube-system, but v2 can do that.
NOTE: Now we're using openstackmagnum dockerhub repo until CPO
team fixing their image release issue.