Don't allow contest.start and contest.stop to be null
Allow admins to limit the localizations of CWS available to users

Co-authored by Luca Wehrstedt.
Add interface for users to choose CWS localization, overriding browser

Co-authored by Luca Wehrstedt.
PEP8
Fix ambiguity in documentation (database setup)
Add entries to .gitignore
Make the testuite start ProxyService and ScoringService w/o contest
Add docstrings.