Test for nonzero length of proj string.
Test for nonzero length of proj string.

Before exporting to PROJ.4.

kapadia/rasterio,snorfalorpagus/rasterio,kapadia/rasterio,youngpm/rasterio,brendan-ward/rasterio,youngpm/rasterio,clembou/rasterio,brendan-ward/rasterio,perrygeo/rasterio,njwilson23/rasterio,johanvdw/rasterio,njwilson23/rasterio,njwilson23/rasterio,youngpm/rasterio,perrygeo/rasterio,perrygeo/rasterio,clembou/rasterio,sgillies/rasterio,brendan-ward/rasterio,clembou/rasterio,kapadia/rasterio,johanvdw/rasterio,johanvdw/rasterio