Client problems due to unsupported response types

[rmiccoli]

Interface problems arise if this query is not empty:

select client_id from client_details where id in (select owner_id from client_response_type where response_type in ("code token id_token", "code token", "token id_token", "id_token"));

There are two workarounds:

1. By querying the database:

delete from client_response_type where response_type in ("code token id_token", "code token", "token id_token", "id_token");

2. By going to the hidden MitreID endpoint (/manage/admin/clients) as admin user and manually unchecking the undesirable response types from the client configuration.

[rmiccoli]

PR #610