These were only exported to facilitate ImageService.GetRepository() (used for
the `GET /distribution/{name:.*}/json` endpoint.
Moving the core functionality of that to the distribution package makes it
more consistent with (e.g.) "pull" operations, and allows us to keep more things
internal.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Sebastiaan van Stijn