What happens during client type transformations:
client types have sense only if the web interface is used;
otherwise only managed clients can be handled;
so client type conversion should happen as close as possible 
to the web code.

revoke:
  managed -> unmanaged: all certificate files are deleted
     asceds-web-unmanaged -r -> asceds-certbot-revoke
  unmanaged -> managed: all certificate files are deleted
     asceds-web-unmanaged -r -> asceds-certbot-revoke

generate (for unmanaged):
  managed -> unmanaged: request_cert.php -> 
     asceds-web-unmanaged -n -> populate ASCEDS_CERT_ID if empty

propagate (for managed):
  unmanaged -> managed: asceds_cert.php -> 
     asceds-web-propagate -> removes web certificate files if
                             ASCEDS_CERT_ID not empty
