Move region policies to DocumentedRuleDefault
Move region policies to DocumentedRuleDefault

A new policy class was introduce that requires
additional parameters when defining policy objects.

This patch switches our region policy object to
the policy.DocumentedRuleDefault and fills the
required policy parameters as needed.

Change-Id: I43c581607b0d0207a27f475b4f4cf8c5c8302e8e
Partially-Implements: bp policy-docs

openstack/keystone,rajalokan/keystone,rajalokan/keystone,openstack/keystone,rajalokan/keystone,openstack/keystone,mahak/keystone,mahak/keystone,mahak/keystone