code: function (client, migrationFolder) {
      events.EventEmitter.call(this);
      if (client === undefined) {
          throw new Error('no client provided');
      }
      _client = client;
  
      this.__defineGetter__('migrationFolder', function () {
          return migrationFolder;
      });
      this.__defineSetter__('migrationFolder', function () {
      });
  }
docs: Changelog is in charge of checking the existence of the migrations reference table,
  creating the migrations reference table  if not available
  and applying the migrations
  @param client inject the client used to perform SQL requests
  @param migrationFolder string The path to the migration files