title: Change default sort order in ActiveAdmin scope
body: <p>For most models, the default sort order (id desc) is fine. But for a couple of scopes on one of my models, it would make more sense to reverse the order, or order by the updated_at field.</p>
  
  <p>I seem unable to achieve this without breaking other functionality, so I'm hoping someone else might teach me how to do this!</p>
  
  <p>I've tried adding a .order() on the objects I'm returning:</p>
  
  <pre><code>scope :example do |models|
    models.order('id asc')
  end
  </code></pre>
  
  <p>This does not seem to have any effect.</p>
  
  <p>I've also tried unscoping, which kind of works. It does sort my objects the way I want to, but it completely breaks all filtering/search functionality.</p>
  
  <pre><code>scope :example do |models|
    models.unscoped.order('id asc')
  end
  </code></pre>
  
  <p>What to do?</p>