Imarok

I added an design mockup in #444 that also includes the filtering for subtitled videos.

> Someone with more ES know how than me can also create an PR for https://github.com/voc/voctoweb/blob/2dacf52972927d005cd1fa6e074c69d46fd270b5/app/models/concerns/elasticsearch_event.rb to boost the conference acronym in the search result ranking Ah, so you can...