GEOMESA-215 GeoMesa query should be exclusive of temporal filter date bo...

...unds for BEGIN, AFTER

* Partitions temporal predicates out and passes them to the STII/AIFI/IndexIterator.
* Adds special handling for DWithin.  (More special cases will be produced as we move away from FilterToAccumulo.)
Thanks to Hunter Provyn for providing the unit tests in FeatureWritersTest.scala.
To the question raised by @elahrvivaz , should we work with a Joda `DateTime` object here on which we explicitly set the time-zone?  The `long` comes from the index-entry, so it represented (presumably) UTC when it was encoded.