CartoDB: add write support

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26474 f0d54148-0727-0410-94bb-9a71ac55c965
gdal_translate: fix logic in detection non-gray color table level (#5245)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26475 f0d54148-0727-0410-94bb-9a71ac55c965