Refs #9 - Country name or iso code instead of country_id.

When creating or updating an address, you can now provide the name or
ISO-code for the country.
When you fetch an address, you still get the country_id. I'm not sure yet
how I will fix this. I asked for more information on the CiviCRM forums:
http://forum.civicrm.org/index.php/topic,35144.0.html