Don't depend on simplejson from Django <1.7

In ``views.py`` there's the following import

```` python
from django.utils import simplejson
````

This fails, as [``django.utils.simplejson`` has been removed](https://docs.djangoproject.com/en/dev/releases/1.7/#features-removed-in-1-7) in Django 1.7.
Merge pull request #8 from stefankoegl/patch-1

Don't depend on simplejson from Django <1.7