title: Why npm installed lots of unexpected modules?
body: <p>I'm using laravel-5.1,with this <code>package.json</code>
  <code>
  {
    "private": true,
    "devDependencies": {
      "gulp": "^3.8.8"
    },
    "dependencies": {
      "laravel-elixir": "^4.0.0",
      "bootstrap-sass": "^3.0.0"
    }
  }
  </code></p>
  
  <p>under root directory,I use <code>npm install</code> command under project root to install <code>laravel-elixir</code> and <code>bootstrap-sass</code>.<br>
  After npm installation finished, I found there were more than 30 node modules under my node_modules diretory,and lots of .cmd files under project root!<br>
  Now I have used git to rollback my project,how to install <code>laravel-elixir</code> and <code>bootstrap-sass</code> correctly using <code>npm</code>?</p>