nodePackages.dat: init at 13.9.2

This adds dat to both nodePackages_6_x and nodePackages_8_x.
This package requires node-gyp-build which is also added to both package sets.
Finally nodePackages_8_x was missing node-gyp and node-pre-gyp.

pkgs/development/node-packages/node-packages-v8.json

@@ -1,9 +1,13 @@
 [
   "bower"
 , "coffee-script"
+, "dat"
 , "grunt-cli"
 , "mocha"
 , "nijs"
+, "node-gyp"
+, "node-gyp-build"
+, "node-pre-gyp"
 , "semver"
 , "sloc"
 ]