Fixed order state not saved on notification in 1.8.1.0

... on payment notifications the order state
(and other changes) are not persisted with Magento
1.8.1.0 because `sendNewOrderEmail()` will reload
all data in the `$order` object

See [our blog post](http://blog.occitech.fr/2014/01/magento-1-8-1-0-changements-sur-lenvoi-demail-de-confirmation-de-commande) (in French) for further details.