Also change it so that if no rules match the delivery, None is returned for 'rule reference' instead of raising a SimulationError, enabling deliveries that are only ever going to be simulated and never created from scratch.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@45621 20353a03-c40f-0410-a6d1-a30d3c3de9de