Implement the archive delete API endpoint.

Also fixed tests not properly skipped in the case Mongo
has no JS support, and improved the test separation
when counters are exercised.
Could you add a test that inserts utopic/mysql-42 but tries to delete (and fails, blob and name still exist)
1) trusty/mysql-42 
2) utopic/mysql-43
Just to make sure, that we don't accidentally delete different series or revisions (a test also for the future).