identity_registration recipes need to be refactored

Every service cookbook has an identity_registration recipe that is nearly identical, which means it is probably a good candidate for refactoring to DRY it up. Perhaps a meta-LWRP in the identity cookbook that does the :create_service, :create_endpoint, :create_tenant, :create_user and :grant_role actions for openstack_identity_register. Without getting too proscriptive in the solution, this needs refactoring.