Create a mapping dict from secgroup id to its name.

def _sg_name_dict(self, sg_id, rules):
        """Create a mapping dict from secgroup id to its name."""
        related_ids = set([sg_id])
        related_ids |= set(filter(None, [r['remote_group_id'] for r in rules]))
        related_sgs = self.client.list_security_groups(id=related_ids,
                                                       fields=['id', 'name'])
        related_sgs = related_sgs.get('security_groups')
        return dict((sg['id'], sg['name']) for sg in related_sgs)