Merge branch 'staging-tagungshaus' into staging

cosinnus_event/admin.py

cosinnus_event/api/serializers.py

cosinnus_event/api/views.py

cosinnus_event/apps.py

cosinnus_event/forms.py

cosinnus_event/hooks.py

cosinnus_event/managers.py

cosinnus_event/migrations/0011_auto_20200916_1431.py

cosinnus_event/migrations/0012_auto_20200925_1635.py

cosinnus_event/models.py

...event/templates/cosinnus_event/conference_event_form.html

...event/templates/cosinnus_event/event_list_conference.html

cosinnus_event/templates/cosinnus_event/list_object.html

cosinnus_event/urls.py

cosinnus_event/views.py