Introduce confident AK messages to organizers and improve wiki export

Implements #51 (closed):

• Introduce model
• Add and link create view
• Visualize in event status dashboard
• Add action to bulk delete after event

Fixes #85 (closed):

Add export template field to Event model and introduce new export page that automatically splits by categories

Implements #90 (closed):

Add links (wiki links and external links) to AK owners in wiki export