Set the billing information country from Express Checkout

I noticed that when the user goes through Paypal EC, and I have the setting:

Update billing customer profiles with address information the customer enters at PayPal.

Paypal EC doesn't update the country of the billing information.

So if my addressfield has a default country, it will always save the billing address with the default country even if the Paypal User perhaps was from another country.

Patch is attached. I'm not sure though if my assumption was correct. If it's not, we can just make the country an empty string to make sure no default value is saved.

Actually, now that I think about it... I'm not even sure why we are assuming the default values are safe to load. I use my default values because I assume that most orders in the store would be in a certain country. That way it's easier/faster for most of my users to fill up the form. But it's not an assumption that all of my orders are in that certain country.