Improve publishing process of validity ranges

• Use form dialog in frontend
• Checks in backend
• Celery task for actual process
• Allow shortening of validity ranges until current date (to end an validity range earlier)

added part::backend part::frontend source::customer::kath type::bug labels

assigned to @hansegucker

marked this issue as related to #4

created branch 10-improve-publishing-process-of-validity-ranges to address this issue

mentioned in merge request !23 (merged)

changed the description

changed milestone to /AlekSIS%"[NLnet #1 (closed)] Fix existing bugs with new timetable"

marked the checklist item Use form dialog in frontend as completed

marked the checklist item Celery task for actual process as completed

marked the checklist item Allow shortening of validity ranges until current date (to end an validity range earlier) as completed

marked the checklist item Checks in backend as completed

mentioned in commit da8b6c2f

closed with merge request !23 (merged)