* Add JSON events API endpoint
* Add regression test for event particulars defaults
* Move JSON events API to a dedicated ActivitiesController
The events endpoint served both the HTML day timeline and the JSON API
feed, but the two paths shared no data or behavior — the HTML side uses
DayTimelinesScoped while the JSON side built its own query. Splitting
into ActivitiesController gives the API its own home at
GET /:account/activities.json without dragging in the timeline
before_actions.
Also preloads comment creator in Event.preloaded to avoid an N+1 when
rendering comment eventables in the JSON feed.
* Split docs/API.md into per-resource sections under docs/api/
* Move API endpoints index above authentication in docs/api/README.md
* Fix trailing comma in boards.md JSON example
* Fix trailing comma in cards.md, add Response label to identity.md, add Rich Text to endpoint index
Rob Zolkos