message: pass error object to the callbacks for failed send Api calls
diff: @@ -157,7 +157,7 @@ function Facebookbot(configuration) {
  if (body.error) {
  botkit.debug('API ERROR', body.error);
  - return cb && cb(body.error.message);
  + return cb && cb(body.error);
  }
  botkit.debug('WEBHOOK SUCCESS', body);
  