Fix storage model.

Steps:
1. Activate your virtualenv.
2. Install south (`pip install south`)
3. Create the database (`python manage.py syncdb`)
4. Migrate forwards (`python manage.py migrate`)
5. Import the initial data (`python manage.py process_data_file data/initial/*.xml`)
6. Import the updated data (`python manage.py process_data_file data/update/*.xml`)