title: Rails 4: Paperclip and rails_admin "undefined method `attachment_definitions' error"
body: <p>I am using rails_admin and paperclip but installing rails_admin with a model having paperclip attributes <code>has_attached_file</code> throws an error</p>
  
  <pre><code>undefined method `attachment_definitions'
  </code></pre>
  
  <p>I am using Rails 4 and rails_admin at master git branch and protected attributes gem.</p>