message: Add ref param to get_messenger_code
diff: @@ -544,11 +544,16 @@ function Facebookbot(configuration) {
  }
  });
  },
  - get_messenger_code: function(image_size, cb) {
  + get_messenger_code: function(image_size, cb, ref) {
  var message = {
  'type': 'standard',
  'image_size': image_size || 1000
  };
  +
  + if(ref) {
  + message.data = {'ref': ref};
  + }
  +
  request.post('https://graph.facebook.com/v2.6/me/messenger_codes?access_token=' + configuration.access_token,
  {form: message},
  function(err, res, body) {
  