Only one setting is now available from the environment:
DJANGO_CONFIG_FILE, it gives a path to a Python that will be executed at
the end of the settings module.
For simpler usage this environment is set by passerelle_manage.py by
passing it a new mandatory option '--config=/path/to/config'.
Tenant settings are now activated by passing the '--multitenant' flag to
passerelle_manage.py.
All OS platform specific paths have been removed, it's expected that
packaging will add them. Debian for example would provide a
debian_config.py file to adapt to its own paths.