Improve control over calls made to IBM Watson

[RafaelAPB]

We may want to impose a limit over calls made to IBM Watson.
A quick option, although insecure, is to save the number of requests per session in a map. If a user utilizes more than x calls, block him until next session.

/*if (requestNumber.get(req.user.email) > 100)    {
    UtilsRoutes.replyFailure(res,e,"Too many requests. Please try later");
    ba_logger.important("BA|CHATBOT|WARNING|TOO MANY REQUEST|" + req.user.email);
    throw new Error ("Too many requests");
}*/

A better solution would be to persist the number of calls, imposing a limit. When the limit is crossed, the calls are blocked for that user, and a timestamp is saved. After x time passes, the user can make calls again.

[RafaelAPB]

let requestNumber = new Map();

[RafaelAPB]

related with #189