GEOMESA-516 Factor out common code in IndexEntry and RasterIndexEntry

* Removed large amounts of duplicated code between IndexEntry and RasterIndexEntry.
* Moved most components into trait.
* Renamed RasterIndex to be RasterIndexEntry
GEOMESA-509 Factor out useful methods out of IndexSchema

* split off sensible things from IndexSchema into a trait.
GEOMESA-462,463 Decoders and Formatters

* wrote decoders and formatters for Raster related Bands and Resolution in Scientific Notation
* updated indexschema.scala to include hooks for resolution and band info.
* made resolution a lexicoded double using mango
* fixed test issue
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
minor cleaning up of code
removing unnecessary code
updating GeoMesaCoverageReader to mosaic GridCoverages and switching to RasterIndexEntry