GEOMESA-330 Avro SimpleFeature's getProperty should return a Property even when the value is null

This addresses an issue found by a user who was attempting to run the Quick Start tutorial.
GEOMESA-328 Fix IndexIterator exception
 * The fix is from @anthony-ccri.
 * The tests show the exceptions which we observed on tablet servers.
GEOMESA-318 Export to STDOUT not working for GML, GeoJSON

Fixed issue with correct output stream not being assigned when exporting.
turning collectStats off
changing logger statements