Include "global" as a country of an exchange

Feature request from fair.coop. They want to create a new exchange that is for the whole world.

In ces_bank.forms.inc line 143, the list of countries can be extended with a new country as "global" or "world" or whatever name:

include_once DRUPAL_ROOT . '/includes/locale.inc';
$countries = country_get_list();

This can be usefull too if an exchange group wants to define its country without state, as Euskadi, Catalonia, Rojava, Palestina, etc...