Speedup the subtitle version list page

We've got reports that this is page is slow, so lets make it faster.
The main objective is to not run queries for every result.
  - Use select_related, this means we don't have to fetch a video for
    each result
  - Use video.title, instead of video.title_display() title_display
    results in a couple queries per result.
  - Don't display parents in list view.  This adds a query per result.

Instead of displaying parent_ids in the list view, run display parents
in the change view.  Also display links instead of raw ids.