GEOMESA-170 - Two query corner cases

* Addressed degenerate intersections in the Geometry utils.
* Properly handles intervals in FilterToAccumulo.
GEOMESA-172 adding try around decoding simple features
GEOMESA-139 Remove inconsistent naming of temporal and geometry attributes in index

Standardize on using geom/dtg for index attributes:
geomesa_index_geometry   --> geom
geomesa_index_start_time --> dtg
and
geomesa_index_end_time   --> dtg_end_time

Reviewed by @anthonyccri
GEOMESA-169 fixing density iterator, restoring expansion of density map