converted from BZ/EPIC to Feature

Feature Overview 
Glance currently lacks per-tenant quota capabilities, which is something that other OpenStack projects have had for quite some time. Especially since Glance is a key project for a working cloud, and because it involves consumption of expensive resources, quotas are necessary for operators to properly restrict usage. Public clouds charge for every resource, and thus per-tenant limits may be less important. However, private clouds generally do not bill for usage, and instead rely on pre-paid quotas for resource sharing.

Goals

• Deliver upstream feature to RHOSO-18
• Customer facing documentation
• Automated Test
• Plan support enablement

Done - Acceptance Criteria (mandatory - Complete while in Refinement status):

1. Unified quota per tenant should work as per upstream spec
2. Full unit test coverage
3. Tempest test coverage running in upstream gates
4. Tempest test coverage running in downstream jobs
5. Manual test with keystone integration.
6. Doc verification