code: function(seriesCallback) {
                  if(!obtainDates) {
                      seriesCallback();
                      return;
                  }
  
                  var pinDateMaps = [];
                  async.eachLimit(boards, 5, function(board, eachCallback) {
                      getDatesForBoardPinsFromRss(board.user, board.board, function(result) {
                          pinDateMaps.push(result);
                          eachCallback();
                      });
                  }, function (err) {
                      if(err) {
                          throw err;
                      }
  
                      var pinDateMap = mergeMaps(pinDateMaps);
  
                      for (var i = 0; i < allPinsData.length; i++) {
                          allPinsData[i].created_at = null;
                          allPinsData[i].created_at_source = null;
                          if (pinDateMap[allPinsData[i].id]) {
                              allPinsData[i].created_at = pinDateMap[allPinsData[i].id];
                              allPinsData[i].created_at_source = 'rss';
                          } else {
                              pinsThatNeedScrapedDates.push(allPinsData[i].id);
                          }
                      }
  
                      seriesCallback();
                      return;
                  });
              }
docs: get what dates we can for pins from the board RSS feeds