hydra: finish RESTfullisation of all endpoints

Currently the endpoints of hydra are still not 100% REST.

The input should be changed as following:

[ ] GET to /api/resources should not pass any resource payload in the body, but be a GET on /api/resources/{resource_id}
[ ] PUT to /api/resources should be a PUT to /api/resources/{resource_id} with the same payload
[ ] DELETE to /api/resources should not pass a payload, but be a DELETE on /api/resources/{resource_id}

also, the responses should be changed as following:

[ ] POST to /api/resources should answer a HTTP Created (201) instead of HTTP OK (200) with "created" as content
[ ] PUT to /api/resources should answer a HTTP OK (200) with empty body instead of HTTP OK (200) with "updated" as content
[ ] DELETE to /api/resources should answer a HTTP OK (200) with empty body instead of HTTP OK (200) with "deleted" as content
[ ] POST to /api/checks should answer a HTTP Created (201) instead of HTTP OK (200)

This will have some impact on udata so this probably should have a twin ticket on udata's side (cc @magopian )

datagouv / hydra