Fixes "ogr2ogr writes to a 'stdout' file instead of writing to the standard output"

I am not sure what this happened at all and I suspect that the ogr2ogr arguments may have changed causing the issue (possibly after GDAL 1.8?).

Long story short - at least on OSX (Lion) and using the lastest version of GDAL (1.9.1), shp2json 0.1.1 will create a file called stdout and write to int instead of writing to the standard output. 

Ref: http://trac.osgeo.org/gdal/ticket/4226

@substack - If you accept the pull request, please update the npm package?