More informative error mailings
This middleware makes the admin error emails a lot more informative: you get the same HTML response that you get with `DEBUG=True`. It uses the base class defined in [#638](http://www.djangosnippets.org/snippets/638/). You will probably want to apply the patch for [#6748](http://code.djangoproject.com/ticket/6748) to help avoid slowdowns caused by unintentional database queries. As the ticket (and django-developers thread) notes, it isn't foolproof; you may still find this executing database queries.
- admin
- debug
- error
- 500