* Display appropriate error when performing unpermitted operation on custom emoji
Fixes#13897
* Remove links to custom emoji actions not performable by moderators
* Fix unused role routes being generated
* Remove unused JavaScript code
* Refactor filters code to be DRYer
* Fix `.count == 0` comparisons to `.empty?` in views
* Fix filters in views
* Add moderator role and add pundit policies for admin actions
* Add rake task for turning user into mod and revoking it again
* Fix handling of unauthorized exception
* Deliver new report e-mails to staff, not just admins
* Add promote/demote to admin UI, hide some actions conditionally
* Fix unused i18n
* Show the local couterpart of emoji when it exists in admin/custom_emojis
* Fix indentation
* Fix error
* Add class table-action-link to Overwrite link
* Make it enable to overwrite emojis
* Make Code Climate happy
ThibG