codespeed doesn't work with Django 1.7

Otherwise fails with:
```
File "/home/kmod/codespeed_env/local/lib/python2.7/site-packages/south/models.py", line 8, in <module>
    raise RuntimeError("South does not support Django 1.7 or higher. Please use native Django migrations.")
RuntimeError: South does not support Django 1.7 or higher. Please use native Django migrations.
```