code: function(callback) {
      var cqlString = 'SELECT * from migrations';
      return this.runSql(cqlString)
        .then(function(data) {
          var sortedData = data.rows.map(function(item) {
            item.moment_time = moment(item.ran_on).valueOf();
            return item
          });
          // Order migration records in ascending order.
          return sortedData.sort(function(x,y) {
            if (x.moment_time > y.moment_time) return -1;
            if (x.moment_time < y.moment_time) return 1;
            return 0;
          })
        })
        .nodeify(callback);
    }
docs: List all existing migrations
  @param callback