Update django debug toolbar to 0.9.4.

We were way behind on a version that didn't work for us.

To test it out, add the following to settings_local.py:

```
MIDDLEWARE_CLASSES += ('debug_toolbar.middleware.DebugToolbarMiddleware',)
INSTALLED_APPS += ('debug_toolbar',)
JINGO_EXCLUDE_APPS += ['debug_toolbar']
```

r?