addressing comments
GEOMESA-552, 553 Refactor GeoMesaCoverageReader to utilize functionality in geomesa-raster, create class to hold GeoMesaCoverageReader parameter values

Removed redundant code in GeoMesaCoverageReader to instead use code in the geomesa-raster project. Also moved code from geomesa-plugin to
geomesa-raster to better structure and organize the project. Added a class to store GeoMesaCoverageReade GeneralParameterValues to aid in
queries for raster images.
addressing comments and cleaning up code