title: django tastypie only fetch a particular field of a particular object
body: <p>In tastypie my url: /api/v1/course/1/?format=json gives the following json:</p>
  
  <pre><code>{
  created_on: "2012-02-27T08:00:54",
  description: "this is course 1",
  id: "1",
  resource_uri: "/api/v1/course/1/",
  subjects: [
      "/api/v1/subject/1/",
      "/api/v1/subject/2/"
  ],
  title: "Course 1"
  }
  </code></pre>
  
  <p>I want to do something like:   </p>
  
  <pre><code>/api/v1/course/1/subjects/?format=json   
  </code></pre>
  
  <p>to get only the list of subjects for a given course. Is this possible?</p>