Stats page errors out with little data

[Chiggins]

Clean install. If there are no questions in the database, there obviously are no responses, so the page errors out.

Exception on /admin/stats [GET]
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1504, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1264, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1262, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1248, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/cahiggi/ILSTUViews/cdw/__init__.py", line 18, in decorated_view
    return fn(*args, **kwargs)
  File "/home/cahiggi/ILSTUViews/cdw/views_admin.py", line 61, in stats
    average_responses = float(total_messages) / float(total_threads)
ZeroDivisionError: float division by zero