Reorganize  code that interfaces to updated wp-e-commerce.js
Before this code gets into the wild it deserves some clean-up.
* cleaned wpsc_update_customer_meta_ajax, removed checkout specific logic from meta update routine wpsc_update_customer_meta_ajax
* new file to hold localization and AJAX processing routines that support wp-e-commerce.js
* moved hook that processes meta on change on shipping same as billing into meta utility file,  it is now with other hooks that do similar meta processing
* use ajax action specifically for updating customer supplied information on checkout or user log form
* include file that handles the localization and ajax interface to wp-e-commerce.js
* removed checkout specific logic from general purpose customer meta update function
*removed JavaScript localizations from country class and moved them the the file that handles all the interfaces to the wp-e-commerce.js
* moved checkout localizations required by the wp-e-commerce.js into the module that handles the interface to the wp-e-commerce.js
* moved functions that provide information about checkout form element status to the js routine in the wp-e-commerce.js interface module

*addresses issue #1138*
Updated function 'wpsc_customer_updated_data_ajax' to be less 'obtuse' in it's processing.
Added some PHPDoc memorializing the format of the returned JSON response
updated code comments
Changed expression

rewrote expression as suggested
Checkout rewind

always rewind after creating checkout
reformatted if tests

using yoda conditions
Fix quote count test

shipping modules may not return a quotes array
Split localization and ajax for checkout

mow two files instead of one
Merge remote-tracking branch 'upstream/master' into pr-issue-1138-js-interface-php-cleanup-merged

Conflicts:
	wpsc-core/js/wp-e-commerce.js
	wpsc-includes/customer-ajax.php
	wpsc-includes/wpsc-countries.class.php