* Add ProvidesMemoryOverhead feature to provide byte overhead for storing cache values
* RandomDataStage
** allow the memory overhead to be set or retrieved from the wrapper featuring ProvidesMemoryOverhead
** allow specifying the total data size, and letting the stage calculate the number of values to put into the cache.
** log the number of words used to generate the string data
* MapReduceStage
** add a parameter to print the result map and object
** ensure that the payload string is always set