message: Update CoreBot.js
  Fix issue with message delay appending delay custom field to timestamp
diff: @@ -886,7 +886,7 @@ function Botkit(configuration) {
  var message = this.messages.shift();
  // make sure next message is delayed appropriately
  if (this.messages.length && this.messages[0].delay) {
  - this.messages[0].timestamp = now.getTime() + this.messages[0].delay;
  + this.messages[0].timestamp = now.getTime() + parseInt(this.messages[0].delay);
  }
  if (message.conditional) {
  