fixup: iofactory allow version > 0

Change-Id: I0cc9bdebef8c0424c29180d3bf3fc857fc59b364
Reviewed-on: http://review.couchbase.org/27778
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>