create the class to groupby Summary

Create the class to do group by summary from CurrencyUnit.
Now is possible have summary in any currencies.


	 GroupMonetarySummaryStatistics groupBy = currenciesToSummary().collect(				groupBySummarizingMonetary());
          Map<CurrencyUnit, MonetarySummaryStatistics> mapSummary = groupBy.get();
          MonetarySummaryStatistics summary = groupBy,get(DOLLAR);