Checkout shipping address and shipping calculator fixes

* Don't overwrite the regions list on jquery document ready, it removes the current selection
* Don't automatically refresh the page on every little shipping address change, it causes the user to lose input focus while typing and odd things happen
* When shipping quotes need to be recalculated display brief informative message to the shopper near the calculate button

**Update 2014-04-19**
* When shipping quotes are known to be invalid hide the shipping quotes table and totals
* Don't recalculate shipping quotes on every HTTP request, especially every AJAX HTTP request
* Recalculate shipping quotes immediately prior to displaying the shipping quotes table in the checkout page

*Note:*
The behavior of automatically selecting a shipping quote after calculation is a little disconcerting. However, I did not change that globally due to concern that there may be places in the code that assume that a shipping quote default has been set.