Merge lp://staging/~michael.nelson/rnr-server/remove-old-exception-middleware into lp://staging/rnr-server

Remove custom exception middleware and rely on oops instead.

Remove some middleware which was created to do essentially what we should be relying on oops for - logging diagnostic info on error - except it does it by temporarily switching to debug=True (I'm assuming that's not thread-safe) and prints out an html debug page into the log, which just leads to unreadable logs.

Instead, on error, a small message is logged in the app log with the oops id, after django's own logging adds the traceback, like this:
{{{
2014-01-03 15:51:45,141 - django.request - ERROR - Internal Server Error: /reviews/
Traceback (most recent call last):
  File "/home/michael/code/rnr/virtualenv/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 115, in get_response
    response = callback(request, *callback_args, **callback_kwargs)
  File "/home/michael/code/rnr/src/reviewsapp/decorators.py", line 63, in wrapper
    result = view(*args, **kwargs)
  File "/home/michael/code/rnr/src/reviewsapp/views/__init__.py", line 43, in overview
    status=ReviewModeration.PENDING_STATUS).count()
  File "/home/michael/code/rnr/virtualenv/local/lib/python2.7/site-packages/mock.py", line 955, in __call__
    return _mock_self._mock_call(*args, **kwargs)
  File "/home/michael/code/rnr/virtualenv/local/lib/python2.7/site-packages/mock.py", line 1010, in _mock_call
    raise effect
ZeroDivisionError: This error is made up.
2014-01-03 15:51:45,147 - root - ERROR - Exception details in OOPS-9b4896b068704cd7a384e66ecaa91149

}}}