[FIX]Delivery: carrier information not propagated from sale order to pickings (Case: ref 595240)

closes lp:1192115
Merge pull request #415 from gurneyalex/7.0-fix_lp1192115-595240-opw-skh

[FIX] delivery: do not remove the delivery method on the sale.order when adding it as an order line (useful information)
Merge branch '7.0' of https://github.com/odoo/odoo into 7.0-linux64