[FIX] point_of_sale: opw-607551, mark the pos order as paid before trying to create...

[FIX] point_of_sale: opw-607551, mark the pos order as paid before trying to create the picking, so in case the picking could not be created for one reason or another, the pos order workflow process continue.

This commit partially reverts rev. 6036 revid:fp@tinyerp.com-20111219220053-tn5gc1lmc13fjpyf, the second part of this commit already has been revert in a previous revision.