No longer show hidden contest in list of all contest but instead hide contests that are over in all other lists

Version 1.0.1

Template 'jwinf': Make contest start button larger, hide link to group management, add coundown in contest view

Fix: Panic on login when username but no password stored in database (possible due to import from foreign contest)

Add database field 'active' for 'taskgroup'. Reset it before contest/task updating, so taskgroups can be removed from contests again. Fixes #12.