Support optimized cinder backend for glance

When Glance is configured with a cinder glance_store, Cinder can be
configured to allow cloning of image data directly in the backend
instead of transferring data through Glance.  Expose these
configuration options in devstack to facilitate testing this feature.

Adds:
- CINDER_ALLOWED_DIRECT_URL_SCHEMES
- GLANCE_SHOW_DIRECT_URL
- GLANCE_SHOW_MULTIPLE_LOCATIONS

Change-Id: Iee619b443088fd77cf7b1a48563203bdf4a93a39
2 files changed