Clean command flag revisions without environment as deleted

[Davidmattei]

The clean command should flag revisions that are not linked to any environment as deleted.

Test query;

select distinct concat(c.name, ':', r.ouuid) as emsLink 
from revision r
join content_type c on c.id = r.content_type_id
where r.ouuid not in (
    select r.ouuid from revision r
    join environment_revision er on r.id = er.revision_id
    group by r.ouuid
) and r.deleted is false;