ActivityPub: Add basic, read-only support for Outboxes, Notes, and Create/Announce Activities (#2197)

* Clean up collapsible components

* Expose user Outboxes and AS2 representations of statuses

* Save work thus far.

* Fix bad merge.

* Save my work

* Clean up pagination.

* First test working.

* Add tests.

* Add Forbidden error template.

* Revert yarn.lock changes.

* Fix code style deviations and use localized instead of hardcoded English text.

app/views/api/activitypub/notes/show.activitystreams2.rabl

@@ -0,0 +1,11 @@
+extends 'activitypub/types/note.activitystreams2.rabl'
+
+object @status
+
+attributes :content
+
+node(:name)         { |status| status.content }
+node(:url)          { |status| TagManager.instance.url_for(status) }
+node(:attributedTo) { |status| TagManager.instance.url_for(status.account) }
+node(:inReplyTo)    { |status| api_activitypub_note_url(status.thread) } if @status.thread
+node(:published)    { |status| status.created_at.to_time.xmlschema }