Create common handlers for address autofilling

[vkublytskyi]

It is a common task to fill region, province, city or street by zip code or suggest zip code based on the already available information. Magento core should provide set of handlers to implement region-specific implementation easier.

Core should include:

1. Listener of zip code field change that will send changed value to registered handler(s). Hendler(s) will return array of fields that may be automatically filled. Implementation of concrete handler is a responsibility of separate modules
2. Possibility to register handler that will return list of possible zip code based on available address data. Implementation of concrete handler is a responsibility of separate modules