title: couldn't find file 'turbolinks' in Rails 4.0.4 app
body: <p>I just upgraded from Rails 3.2.17 to 4.0.4 and everything looks great. I copied over a lot of the config files from a brand new test 4.0.4 app I created. However, when I add in the following line to my <code>app/assets/javascripts/application.js</code> file, I get an error:</p>
  
  <pre><code>//= require turbolinks
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>couldn't find file 'turbolinks'
    (in /Users/scott/Code/ucode/app/assets/javascripts/application.js:15)
  </code></pre>
  
  <p>I want turbolinks. I'm on Rails 4.0.4. My test app didn't have this error. Why am I getting this error and how do I fix it? I also updated my <code>app/views/layouts/application.html.erb</code> file to include:</p>
  
  <pre><code>&lt;%= javascript_include_tag "application", "data-turbolinks-track" =&gt; true %&gt;
  </code></pre>