message: Add fb app secret prood while creating message creative
diff: @@ -1064,6 +1064,10 @@ function Facebookbot(configuration) {
  create_message_creative: function(message, cb) {
  var uri = 'https://' + api_host + '/' + api_version + '/me/message_creatives?access_token=' + configuration.access_token;
  + if (facebook_botkit.config.require_appsecret_proof) {
  + uri += '&appsecret_proof=' + appsecret_proof;
  + }
  +
  var messageToBroadcast = {};
  if (typeof(message) == 'string') {
  