code: function responseCallback(response, model, success) {
          // Add response to a hash that will eventually be returned through the promise
          responses[model.cid] = {
              success: success,
              response: response
            };
          // If we have reached the total of number of expected responses, then resolve or reject the promise
          if (responsesFailed + responsesSucceeded === numberOfSaves) {
            if (responsesFailed > 0) {
              // Rollback if any responses have failed
              if (options.rollback) {
                _.each(formModel.getTrackedModels(), function(model) {
                  model.set(oldValues[model.cid]);
                  if (responses[model.cid].success) {
                    model.save();
                  }
                });
              }
              formModel.trigger('save-fail', responses);
              deferred.reject(responses);
            } else {
              formModel.trigger('save-success', responses);
              deferred.resolve(responses);
            }
          }
        }
docs: Callback for each response