Added ConstantTile writing through ArgWriter.

 - Refactored Geotools GeoTiff reader, moved the Reader and Writer stuff to ascii, since that's the only format still using that architecture.
Merge remote-tracking branch 'upstream/master' into write-constant-raster
Fixed gdal test
Merge remote-tracking branch 'upstream/master' into write-constant-raster
Fixed GDAL test
Merged in upstream.
Merge remote-tracking branch 'origin/write-constant-raster' into write-constant-raster
Merge remote-tracking branch 'upstream/master' into write-constant-raster
Removed test on deleted reprojection code.
Fixed RowTransform test.
Merge pull request #884 from lossyrob/write-constant-raster

Write Constant tile, cleanup of geotrellis.raster.io