Update nan and node-pre-gyp deps
Update nan and node-pre-gyp deps

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