* Improve webfinger templates and make tests more flexible
* Clean up AS2 representation of actor
* Refactor outbox
* Create activities representation
* Add representations of followers/following collections, do not redirect /users/:username route if format is empty
* Remove unused translations
* ActivityPub endpoint for single statuses, add ActivityPub::TagManager for better
URL/URI generation
* Add ActivityPub::TagManager#to
* Represent all attachments as Document instead of Image/Video specifically
(Because for remote ones we may not know for sure)
Add mentions and hashtags representation to AP notes
* Add AP-resolvable hashtag URIs
* Use ActiveModelSerializers for ActivityPub
* Clean up unused translations
* Separate route for object and activity
* Adjust cc/to matrices
* Add to/cc to activities, ensure announce activity embeds target status and
not the wrapper status, add "id" to all collections
