Save a workflow
        obj - instance of a workflow to save
        run_id - unique id to give the run

def save(self, obj, run_id):
        """
        Save a workflow
        obj - instance of a workflow to save
        run_id - unique id to give the run
        """
        id_code = self.generate_save_identifier(obj, run_id)
        self.store.save(obj, id_code)