Worldwide shipping

[djbooth007]

Sellers willing to risk posting product anywhere should be able to select 'Worldwide' from countries to ship to.

Edit: Also make worldwide shipping the default selection.

[drwasho]

Just to add to this, we should include continents/regions:

1. Europe
2. Asia
3. Pacific (technically Australia, we could put Asia-Pacific/Australia)
4. Africa
5. North America
6. South America
7. Antarctica

[cpacia]

needs to match this list https://github.com/OpenBazaar/OpenBazaar-Server/blob/master/protos/countries.proto