Improve blank and unique constraints of model:
- allow blank starting times of slotes to store durations before scheduling and adapt string representation
- change unique constraint from name and shortname of AK to unique for each event only
Implement handling of tags for submission and update (auto-creation) by using a semicolon-separated text file instead of multiple choice field
Implement handling of durations for submission
Automatically generate short name
Use different forms for submission and update
Use special adapted template for AK updates instead of submission template
Fix EventSlugMixin for POST requests

Add choosen-js library and assets for nicer looking multiple select
Add new blocks for loading of individual assets to base template
Use choosen-js for multiple fields in AK submission view

currently only works when creating a new owner

create template for AK wish submission
create form for AK wish submission
create view for AK wish submission
adapt urls and buttons

Add TODOs for other data manipulation/auto-creation/...-tasks

exclude interest
exclude track

create form class
create template
configur urls
create submission view