We're filtering the events using `Event#visible_to_user?`.
At most we're loading 100 events at once.
Pagination is also dealt with in the finder, but the resulting array
is wrapped in a `Kaminari.paginate_array` so the API's pagination
helpers keep working. We're passing the total count into that
paginatable array, which would include confidential events. But we're
not disclosing anything.
* Meld the following disparate endpoints:
* `/projects/:id/events`
* `/events`
* `/users/:id/events`
+ Add result filtering to the above endpoints:
* action
* target_type
* before and after dates
