Fix 500 when saving /site/edit without email
When saving /site/edit with no no_reply_email set, a 500 error page
would be returned due to an empty value being passed as value to
the datastore (which is not allowed for email fields).
#!/usr/bin/env python
"""
Daily cleanup job.
Can be run as a cronjob to clean out old data from the database (only expired
sessions at the moment).
"""
from django.core import management
if __name__ == "__main__":
management.call_command('cleanup')