A buyer can cancel the hold invoice in status waiting-payment, but the order is not cancelled

[Catrya]

If the maker of a purchase order sends action cancel to Mostro when the order is in status waiting-payment, the order will not be cancelled, the buyer will receive Action: CantDo. However, the hold invoice is cancelled, it goes from "state": "OPEN", to "state": "CANCELED".

Steps to reproduce it:

1. The buyer creates a purchase order
2. The seller takes it. Order goes to status waiting-payment. Mostro creates a hold invoice with "state": "OPEN"
3. The buyer sends the cancel action before the seller pays the invoice. The order remains in status waiting-payment, but the hold invoice goes to "state": "CANCELED"

I think the suggestion in issue #379 should be followed and the order should be cancelled.