Don't default country and region on forms

**Addressing issue #1084...**
* The change removes the defaults to base country and region
* A "please select a country" or "please select a {region} placeholder will be added to the dropdowns.
* If a country or region is not current for the user the please select message will be the default
* the country meta value "region_label" is used to form the please select message for a region
* if a region_label meta is not found the default wpsc string "state/province" is used
* When dropdowns are created there is logic to be sure an HTML element id is not re-used.  If a duplicated where to happen the string '-2', '-3'm etc would be applied to element ids after the first element.
* The drop downs will default to the one country in the lsit if there is only one country in the list

**Also...**
* Added ability to define meta value defaults for WPSC_Country class meta properties.  Used this new feature to manage the default from "region_label".