title: Upgrading to Ruby on Rails 3.1: the 'jquery_ujs.js' file should be deleted?
body: <p>I am using Ruby on Rails 3.0.10 and I am upgrading my RoR to the version 3.1.0. I am following the <a href="http://railscasts.com/episodes/282-upgrading-to-rails-3-1" rel="nofollow">Upgrading to Rails 3.1</a> railscast and on the time <em>05:14</em> he deletes all related jQuery files present in the <code>assets/javascripts/</code> directory.</p>
  
  <p>In the linked railscast there are these 3 files:</p>
  
  <pre><code>jquery.js
  jquery.min.js
  rails.js
  </code></pre>
  
  <p>On my machine there are these 3 files:</p>
  
  <pre><code>jquery.js
  jquery.min.js
  jquery_ujs.js
  </code></pre>
  
  <p>The difference is that I have the <code>jquery_ujs.js</code> file instead of the <code>rails.js</code> file... <strong>what I have to do? That is, should I delete the <code>jquery_ujs.js</code> file?</strong></p>