Adapt flask_wtf changes
Adapt flask_wtf changes

fixes #55

eXma/meet-and-eat-registration-system,janLo/meet-and-eat-registration-system,janLo/meet-and-eat-registration-system,janLo/meet-and-eat-registration-system,eXma/meet-and-eat-registration-system,janLo/meet-and-eat-registration-system,eXma/meet-and-eat-registration-system,eXma/meet-and-eat-registration-system