no need to initialise std::ostringstream with an empty string.
no need to initialise std::ostringstream with an empty string.

tomhughes/node-mapnik,mapnik/node-mapnik,tomhughes/node-mapnik,mapnik/node-mapnik,mapnik/node-mapnik,mapnik/node-mapnik,tomhughes/node-mapnik,mapnik/node-mapnik,tomhughes/node-mapnik,tomhughes/node-mapnik