message: Add custom label_id
diff: @@ -852,13 +852,17 @@ function Facebookbot(configuration) {
  }
  });
  },
  - send: function(message_creative_id, cb) {
  + send: function(message_creative_id, custom_label_id, cb) {
  var uri = 'https://' + api_host + '/' + api_version + '/me/broadcast_messages?access_token=' + configuration.access_token;
  var body = {
  'message_creative_id' : message_creative_id
  };
  + if(custom_label_id) {
  + body['custom_label_id'] = custom_label_id;
  + }
  +
  request({
  method: 'POST',
  json: true,
  