title: Excluding directory
body: <p>I am working on a django project and am trying to run pyflakes on an app in it. I need to exclude the "migrations" directory from pyflakes. </p>
  
  <p>For pep8 I can do </p>
  
  <pre><code>pep8 --exclude=migrations app_name
  </code></pre>
  
  <p>Is there any similar way for pyflakes? </p>
  
  <p>I couldn't find any proper documentation for pyflakes.</p>