Change FB text limit to 640 rather than 320
Change FB text limit to 640 rather than 320

* See FB docs: https://developers.facebook.com/docs/messenger-platform/send-api-reference/text-message

dehghanfar/apiaiErfanTest,EMMInc/newconverse,thomascorriente/janis-fusion,Mohammad-Alsadi/connoxchatbottest,EMMInc/newconverse