Form integration and js API

[jedateach]

This module should provide some useful forms / fields for making use of this module.

When country changes, an ajax call is made to the server to get states. If response is empty, then state is a text field, otherwise it is a dropdown field.

Note that this enforces the use of javascript. A form-only approach would require 'set' and 'update' buttons next to fields, which would refresh the page. Probably too difficult to achieve nicely.

[jedateach]

I have a simple implementation working, where the region field gets updated when you select a country. There are still a number of issues to deal with however:

• Set region by id, rather than name. What about countries with no region?
• Validation - is it now broken for that field?
• Handle pre-populated data
• 3rd-level handling?
• Show spinner & disable during changeover

Introduced in 73dff61