title: Protecting files?
body: <p>Can I have a permissions-managed list of files in KeystoneJS in which not only the list is protected (let's say I have a list of PDFs on a page that only logged-in users can see) but the files themselves are as well? For example, if I have a list of PDFs on a password-protected page, if I copy the URL of one of those PDFs to a separate browser and paste it in, will I be able to access that file since I'm not logged in?</p>
  
  <p>Currently, ApostropheCMS seems to do what I need it to as far as handling files as content well, permissions, etc., but there is no built-in way to protect the files themselves. Would be great if there was a way in Keystone to accomplish this.</p>