Update util to v0.11.0.

Author: goto-bus-stop

package.json

@@ -29,7 +29,7 @@
     "timers-browserify": "^2.0.2",
     "tty-browserify": "0.0.0",
     "url": "^0.11.0",
-    "util": "^0.10.3",
+    "util": "^0.11.0",
     "vm-browserify": "0.0.4"
   },
   "homepage": "http://github.com/webpack/node-libs-browser",