This adds the basic framework for registering and using default policy
rules. Rules should be defined and returned from a module in
heat/policies/, and then added to the list in heat/policies/__init__.py.
new policy wrapers `registered_identified_stack` and
`registered_policy_enforce` has been added for policy enforcement of
registered rules with same parameter as `identified_stack` and
`policy_enforce` besides set `is_registered_policy` flag to true.
This flag will decide to use new policy framework or not.
Now we can use `tox -e genpolicy` to check and generate policy file.
Change-Id: I7a232b3ea7ce0f69a5b7ffa278ceace7a76b666f
Partially-Implements: bp policy-in-code
b171490450