title: couldn't find file 'jquery' in Rails project
body: <p>I'm working through the Agile Web Development book with Rails version 3.2.13 and Ruby 2.0.0, but I keep getting the following error when trying to access <code>localhost:3000</code>:</p>
  
  <p><code>Sprockets::FileNotFound in Store#index</code></p>
  
  <p><code>couldn't find file 'jquery' (in /Users/.../app/assets/javascripts/application.js:13)</code></p>
  
  <p>My <code>application.js</code> file:</p>
  
  <pre><code>// This is a manifest file that'll be compiled into application.js, which will include all the files
  // listed below.
  //
  // ...
  //    
  //= require jquery
  //= require jquery-ui
  //= require jquery_ujs
  //= require_tree .
  </code></pre>
  
  <p>In my <code>Gemfile</code>, I have <code>gem 'jquery-rails', '~&gt; 2.3.0'</code> and have attempted many different solutions I found on the internet to no avail.</p>