[view] attachments view
[concern] refacotred polymorhic controller
[routes] attachments routes
[spec/features] attachments under exam portionsa
[controller] attachments controller
[controller] clean unnecessery code from exam controller
[controller] set attachable for exam portion
[controller] remove unecessery controller
satisfy houndci
Merge pull request #318 from Genshin/refactor_and_ajaxify_attachments

Refactor and ajaxify attachments