title: gitignore all files of extension in directory
body: <p>Is there a way to ignore all files of a type in a directory?</p>
  
  <p><code>**</code> is apparently meaningless to git, so this doesn't work:</p>
  
  <pre><code>/public/static/**/*.js
  </code></pre>
  
  <p>The idea is to match arbitrary nested folders.</p>