title: How to include javascript in middleman 4?
body: <p>I've been using Middleman for a while and it always used the Rails asset pipeline for including javascript and css. So to include a javascript module called "thing.js" in the same directory, you'd do:</p>
  
  <pre><code>//= require thing
  </code></pre>
  
  <p>But since Middleman 4, that seems to have changed and I can't find any documentation. The closest thing I can find is this page which shows me how to run an ember.js compilation: <a href="https://middlemanapp.com/advanced/external-pipeline/" rel="nofollow">https://middlemanapp.com/advanced/external-pipeline/</a></p>
  
  <p>So... if I want to load javascript files in Middleman now, do I have to roll my own build system? Or am I missing something?</p>