GEOMESA-443 Test TimeSnap and GridSnap corner cases

* Adds tests for TimeSnap class.
* Adds corner case test for GridSnap and addresses a corner case.
GEOMESA-445 Create Temporal Density Iterator
GEOMESA-490 removing objenesis, vecmath, jgraphx, snappy and jline

* Had to also remove DBScan process, which relied heavily on vecmath
* Objenesis is still a test dependency
GEOMESA-498 adding filters to modify feature writer
GEOMESA-452 Accumulo Coverage Format connection parameters aren't saved in Geoserver

* Connection parameters in the datastore form are set using values parsed out from the coverage url
* Shared FORMAT between CoverageReader and CoverageStoreEditPanel
GEOMESA-493 geomesa-raster module

added geomesa-raster module to project
GEOMESA-433,GEOMESA-434,GEOMESA-484 Develop raster and ingest handling code for integration with GeoMesa. Implement raster ingest as a new maven submodule. Create a new Store for raster data.
still a work in progress for GM-489, 473, 471
renamed to Geomesa Coverage Format, added @wjp22903's work for image serialization, small UI changes