We will need:

ImageService
a service that can do crud on image information.  not user-specific. opaque
image ids.

GlanceImageService(ImageService):
image ids are URIs.

LocalImageService(ImageService):
image ids are random strings.

OpenstackAPITranslationStore:
translates RS server/images/flavor/etc ids into formats required
by a given ImageService strategy.

api.openstack.images.Controller:
uses an ImageService strategy behind the scenes to do its fetching; it just
converts int image id into a strategy-specific image id.

who maintains the mapping from user to [images he owns]?  nobody, because
we have no way of enforcing access to his images, without kryptex which
won't be in Austin.
