title: select_related() in generic class-based views
body: <p>I'm just getting started with the new(ish) class-based views, and I am wondering what's the best way to get select_related() in there. Here's my view:</p>
  
  <pre><code>class PostDetailView(DetailView):
      model = Post
  </code></pre>
  
  <p>The post comes from the 'slug' in the URL. This works fine, but, I would like to get select_related() in there to reduce the number of queries.</p>