#272 retake - Add post database events and review event names

This is another try on #272

This follows what @girogiro suggested as naming for events
- GET: none / on_fetched_item, on_fetched_resource
- POST: on_insert / on_inserted,
- PATCH: on_update / on_updated,
- PUT: on_replace / on_replaced,
- DELETE: on_delete_item, on_delete_resource / on_deleted_item, on_deleted_resource

For sure this patch needs some work, but having the weekend ahead I leave you here the bulk of the job, including grouping event tests in method tests. Check it out, bash it, comment on it :)