'Return a list of dictionaries indicating the members of the
image, i.e., those tenants the image is shared with.
:param req: the Request object coming from the wsgi layer
:param image_id: The image identifier
:returns: The response body is a mapping of the following form
{\'members\': [
{\'member_id\': <MEMBER>,
\'image_id\': <IMAGE>,
\'status\': <MEMBER_STATUS>,
\'created_at\': ..,
\'updated_at\': ..}, ..'

def index(self, req, image_id):

    image = self._lookup_image(req, image_id)
    member_repo = self._get_member_repo(req, image)
    members = []
    try:
        for member in member_repo.list():
            members.append(member)
    except exception.Forbidden:
        msg = (_('Not    allowed    to    list    members    for    image    %s.') % image_id)
        LOG.warning(msg)
        raise webob.exc.HTTPForbidden(explanation=msg)
    return dict(members=members)
