feat(npm-info): support private modules

closes #28

lib/npm-info.js

@@ -1,28 +1,41 @@
 'use strict'
 
+var async = require('async')
+var npmconf = require('npmconf')
 var request = require('request')
 
-var efh = require('./error').efh
-
 module.exports = function (pkgName, cb) {
-  var encodedPkgName = pkgName.replace(/\//g, '%2F')
-  request(process.env.npm_config_registry + encodedPkgName, efh(cb)(function (response, body) {
-    var res = {
-      version: null,
-      gitHead: null,
-      pkg: null
+  var registry = process.env.npm_config_registry
+  async.waterfall([
+    npmconf.load,
+    function (conf, callback) {
+      var cred = conf.getCredentialsByURI(registry)
+      callback(null, {
+        url: registry + pkgName.replace(/\//g, '%2F'),
+        headers: {
+          'Authorization': cred.token ? 'Bearer ' + cred.token : null
+        }
+      })
+    },
+    request,
+    function (response, body, callback) {
+      var res = {
+        version: null,
+        gitHead: null,
+        pkg: null
+      }
+
+      if (response.statusCode === 404 || !body) return callback(null, res)
+
+      var pkg = JSON.parse(body)
+
+      if (pkg.error) return callback(pkg.error)
+
+      res.version = pkg['dist-tags'].latest
+      res.gitHead = pkg.versions[res.version].gitHead
+      res.pkg = pkg
+
+      callback(null, res)
     }
-
-    if (response.statusCode === 404 || !body) return cb(null, res)
-
-    var pkg = JSON.parse(body)
-
-    if (pkg.error) return cb(pkg.error)
-
-    res.version = pkg['dist-tags'].latest
-    res.gitHead = pkg.versions[res.version].gitHead
-    res.pkg = pkg
-
-    cb(null, res)
-  }))
+  ], cb)
 }