adds datetimefield for start to Event model
adds datetimefield for start to Event model
adds translations
adds migration

The wizard is used instead of the normal built-in creation workflow
It consists of multiple steps to specify the most fundamental settings (especially the timezone), further settings, copying AKCategories and AKRequirements from existing events and activating the event once the basic configuration is done
The steps after the creation (first two steps) can be skipped

Implements #47
Link from event status admin view
Update translations

Attach status view to event model admin
Link from admin start page
Customize admin interface headers
Update translations

Introduce new mixin
Replace edit & create views by redirects to overview page
Prevent inserting/updating for AKs and Owners
Disable interest counter
Hide interest button
Update translations

adjust other buttons
re-generate translations

Adapt settings
Add i18n urls to central url conf
Add language chooser to base.html
Adapt readme and utils