code: function combineStatsAndIndexes(done, results) {
    var indexes = results.getIndexes;
    var stats = results.getIndexStats;
    var sizes = results.getIndexSizes;
    _.each(indexes, function(idx, i) {
      _.assign(indexes[i], stats[idx.name]);
      _.assign(indexes[i], sizes[idx.name]);
    });
    done(null, indexes);
  }
docs: merge all information together for each index
  @param  {Function} done       callback
  @param  {object}   results    results from async.auto