title: reverse lookup by ForeignKey in Tastypie
body: <p>I have a post model and a comment model that holds the comments that were made for a particular post.</p>
  
  <pre><code>class Post(models.Model):
      body = models.TextField()
      user = models.ForeignKey(User)
  
  class Comment(models.Model):
      post = models.ForeignKey(Post)
      date = models.DateTimeField(auto_now_add=True)
      comment = models.TextField()
      comment_user = models.ForeignKey(User)
  </code></pre>
  
  <p>Now I want my Post resource to include URI to all the comments attached to a particular post.</p>
  
  <p>I do know I can use <code>fields.ForeignKey</code> to represent which post my comments belong to, but I want the API to have the URI of all the comments that belong to the post in the post object. I hope that makes sense.</p>