This patch adds access to new REST API for config and service
metadata retrieval.
The following work has been done:
* Create new manager for config retrieval
* Create new Resource and CRUD manager for service info retrieval
* Add managers to client
* Add new CLI command and openstack client entries
Change-Id: I43f572202b1cd3832a820f46f7c7b44a0d998406
Depends-on: https://review.openstack.org/#/c/406180/