message: Add get_target_audience
diff: @@ -502,6 +502,9 @@ function Facebookbot(configuration) {
  delete_target_audience: function() {
  facebook_botkit.api.messenger_profile.deleteAPI('target_audience');
  },
  + get_target_audience: function(cb) {
  + facebook_botkit.api.messenger_profile.getAPI('target_audience', cb);
  + },
  postAPI: function(message) {
  request.post('https://graph.facebook.com/v2.6/me/messenger_profile?access_token=' + configuration.access_token,
  {form: message},
  