prefer local over global npmrc file (#39)

* feat(npmrc): prefer local over global rc file

* chore(misc): fix capitalisation

* chore(debug): use debug instead of console.log

* fix(npmrc): move logic into separate npm module

* fix(npmrc): remove example registry url

package.json

@@ -36,10 +36,10 @@
     "del": "2.2.2",
     "ggit": "1.13.4",
     "lazy-ass": "1.5.0",
+    "local-or-home-npmrc": "1.0.0",
     "q": "2.0.3",
     "registry-url": "3.1.0",
     "repo-url": "1.0.0",
-    "user-home": "2.0.0",
     "verbal-expressions": "0.2.1"
   },
   "devDependencies": {

src/set-auth-token.js

@@ -1,17 +1,18 @@
 'use strict'
 
 var registryUrl = require('registry-url')
-var userHome = require('user-home')
-var join = require('path').join
-var npmrcFile = join(userHome, '.npmrc')
 var fs = require('fs')
 var q = require('q')
 var formUrlToken = require('./form-auth-token')
 var getPackage = require('./get-package')
+var npmrcFile = require('local-or-home-npmrc')
+var debug = require('debug')('npm-utils')
 
 function updateNpmrc (data) {
   var contents = ''
+
   if (fs.existsSync(npmrcFile)) {
+    debug('using file:', npmrcFile)
     contents = fs.readFileSync(npmrcFile, 'utf-8')
     contents = contents.trim() + '\n'
   }