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
Ensure  array() is always defined in wpec_taxes::wpec_taxes_set_options()
In wpec_taxes::wpec_get_counry_information,  should be an array, not a boolean
Define label and country_code inside wpsc_update_location_labels, once and for all.
More once-and-for-allness.  Also, billing_state_elements with literally defined twice.
Ensure  variable is available for all execution paths in wpsc_currency_display.
Remove dead  variable in WPSC_Region constructor, also define  for all execution paths.  Needs review from @JeffPyeBrook.
Use proper saving method for WPSC_Region class.  Seems to be a copypasta issue here.  Also, need a second look at the WPSC_Region::as_array() method here.
Removed dead variable in WPSC_Region::_save_region_data()
Ensure  is always defined in WPSC_Region::_save_region_data().  Also, ensure deprecated visitor checkout meta is properly updated.  Needs review from @JeffPyeBrook
Use proper class and method in shipping helper to get country name.
Define  for all execution paths.
Explcitly declare parsed args in this function.  Though not intended for outside usage, it shouldn't break if it is used elsewhere.
Typos and doc fixes (first pass, not finished) on WPSC_Countries.  More importantly, and the change needing review from @JeffPyeBrook - uses WPSC_Data_Map::value(), instead of the non-existent WPSC_Data_Map::get(), in WPSC_Countries::get_country_isocode()