use path trick to load local util module

Gets around the node.js limitation of always loading core modules even
if you have the same name installed locally.

assert.js

@@ -25,7 +25,7 @@
 // when used in node, this will actually load the util module we depend on
 // versus loading the builtin util module as happens otherwise
 // this is a bug in node module loading as far as I am concerned
-var util = require('./node_modules/util');
+var util = require('util/');
 
 var pSlice = Array.prototype.slice;