basic support for GDAL 2.0

git-svn-id: http://svn.osgeo.org/postgis/trunk@12584 b70326c6-7e19-0410-871a-916f4a2858ee
add news for GDAL 2.0

git-svn-id: http://svn.osgeo.org/postgis/trunk@12585 b70326c6-7e19-0410-871a-916f4a2858ee