messenger-profile-api and handover-protocol APIs, code refactoring

[madEng84]

Hi guys, as I told you some months ago, i had to deploy some chatbots. I have used your Bot and customized it for my needs I have created two chatbots, one of them used by a webhook fullfillment for a DialogFlow Application associated to a Facebook App

So i did a lot of changes

I have implemented:

• API for Configurations for Facebook bot (see Facebook Docs)
• possiblity to return data (see do_send variable) instead of calling Chatbot directly, useful for DialogFlow Bots
• API for Handover Protocol (see Facebook Docs) if you want to "pause" automatic responses e pass the control to an other Bot

Unfortunately i did no tests, but I would be very happy if my changes were available to everyone, so as to improve the code in both style and functionality.

Thank you in advance

Have a nice weekend