Glance Metadata Definitions Catalog - DB

Implements: blueprint metadata-schema-catalog

A common API hosted by the Glance service for vendors, admins,
services, and users to meaningfully define available key / value
pair and tag metadata. The intent is to enable better metadata
collaboration across artifacts, services, and projects for
OpenStack users.

This is about the definition of the available metadata that can
be used on different types of resources (images, artifacts,
volumes, flavors, aggregates, etc). A definition includes the
properties type, its key, it's description, and it's constraints.
This catalogue will not store the values for specific instance
properties.

Change-Id: I01cc63df3d3abe383c94cfb54598868b4bb729bb
DocImpact
Co-Authored-By: Lakshmi N Sampath <lakshmi.sampath@hp.com>
Co-Authored-By: Wayne Okuma <wayne.okuma@hp.com>
Co-Authored-By: Travis Tripp <travis.tripp@hp.com>
Co-Authored-By: Pawel Koniszewski <pawel.koniszewski@intel.com>
Co-Authored-By: Michal Jastrzebski <michal.jastrzebski@intel.com>
Co-Authored-By: Michal Dulko <michal.dulko@intel.com>
Merge "Glance Metadata Definitions Catalog - DB"