update packages to latest version

node_modules/npm/lib/cache/cached-package-root.js

@@ -0,0 +1,14 @@
+var assert = require("assert")
+var resolve = require("path").resolve
+
+var npm = require("../npm.js")
+
+module.exports = getCacheRoot
+
+function getCacheRoot (data) {
+  assert(data, "must pass package metadata")
+  assert(data.name, "package metadata must include name")
+  assert(data.version, "package metadata must include version")
+
+  return resolve(npm.cache, data.name, data.version)
+}