Fix fatal error with custom Country and StateProvince

When submitting data to CRM_Core_BAO_CustomValueTable::setValues() it would throw a fatal error if one of the fields was type state or country. I finally tracked this to CRM_Utils_Type::escape() which was not aware of those data types. This patch adds them, using the same rule as positive integer. This may not be the totally correct solution, but it does fix the problem.

See: http://drupal.org/node/1246964