Update to Django 1.7

Starting point for #122
like this?
```
    djangogirls
    ├── mysite
    |       __init__.py
    |       settings.py
    |       urls.py
    |       wsgi.py
    ├── manage.py
    └── blog
        ├── migrations
        |    	__init__.py
        ├── __init__.py
        ├── admin.py
        ├── models.py
        ├── tests.py
        └── views.py
```