Ensure that a key is only assigned once
Ensure that a key is only assigned once

By updating at the same time as the select, we're ensuring that no two
users will get the same license key, as was report by Tokyo

Change-Id: Id2469b911f4e76f3aa391d351df507f9163a010a

freerunningtech/spree-license-key,StemboltHQ/spree-license-key,project-eutopia/spree-license-key,freerunningtech/spree-license-key,degica/spree-license-key,StemboltHQ/spree-license-key,degica/spree-license-key,project-eutopia/spree-license-key,project-eutopia/spree-license-key,degica/spree-license-key