This code retries to load sessions three times. If not an error will be
thrown. There are other solutions (Like not throwing the error), but
I would like to see errors in production usage to see, if this helps or
not.
- removed big mode artifacts
- removed django_session_redis
- Enforce newly created settings.py when invalid options are set:
* OPENSLIDES_USER_DATA_DIR
* SESSION_ENGINE
- Overwrites the secret key during development to "development"