fixed warning caused by django 1.5 update

[bpoetz]

I just changed the urls.py file to replace the deprecated

django.conf.urls.defaults 

with

django.conf.urls 

as found in the warning message. Here's the relevant code from ..defaults.py:

import warnings
warnings.warn("django.conf.urls.defaults is deprecated; use django.conf.urls instead",
          DeprecationWarning)

from django.conf.urls import (handler403, handler404, handler500,
    include, patterns, url)

Hopefully this isn't considered too trivial, it's my first pull request, be gentle.