message: Add FB insights API
  Fix log
diff: @@ -815,9 +815,46 @@ function Facebookbot(configuration) {
  });
  };
  + var insights_api = {
  + get_insights: function (metrics, since, until, cb) {
  + var uri = 'https://' + api_host + '/v2.8/me/insights?access_token=' + configuration.access_token;
  + if (metrics) {
  + if (typeof(metrics) == 'string') {
  + uri += '&metric=' + metrics;
  + } else {
  + uri += '&metric=' + metrics.join(',');
  + }
  + }
  +
  + if (since) {
  + uri += '&since=' + since;
  + }
  + if (until) {
  + uri += '&until=' + until;
  + }
  + request({
  + method: 'GET',
  + json: true,
  + uri: uri
  + }, function (err, res, body) {
  + if (err) {
  + facebook_botkit.log('Could not call Facebook Insights API', err);
  + cb(err);
  + } else {
  + if (body.error) {
  + facebook_botkit.log('ERROR in Facebook Insights API call: ', body.error.message);
  + cb(body.error);
  + } else {
  + facebook_botkit.log('Successfully got Facebook Insights API');
  + cb(null, body);
  + }
  + }
  + });
  + }
  + };
  facebook_botkit.api = {
  @@ -827,6 +864,7 @@ function Facebookbot(configuration) {
  'attachment_upload': attachment_upload_api,
  'nlp': nlp,
  'tags': tags,
  + 'insights': insights_api
  };
  