title: render partial with slim-lang grunt-slim plugin throws "undefined method render"
body: <p>I'm trying to work with slim-lang for my web project. I have the following setup:</p>
  
  <ul>
  <li>ruby 2.0</li>
  <li>rails 4.0</li>
  <li>node v0.10.17</li>
  </ul>
  
  <p>This setup is working with grunt and the grunt-slim plugin.</p>
  
  <p>At first glance, the slim templates compile all right, but when I try to work with partials, I get an error:</p>
  
  <pre><code>NoMethodError: undefined method `render' for #Object:0x000000029db190
  </code></pre>
  
  <p>Example code to reproduce:</p>
  
  <p>_foo.slim:</p>
  
  <p><code>a (href="#") click</code></p>
  
  <p>bar.slim:</p>
  
  <p><code>= render 'foo'</code></p>
  
  <p>I'm a front end developer, so I don't know enough about ruby or rails. I don't understand what causes this error-- is it the grunt-slim plugin or something to do with ruby?</p>
  
  <p>Any help will be appreciated! </p>