Clear temporary data, whether in cache or in transient
* Checks options tables for transients and delete them if appropriate
* Fires action hooks so themes, classes, plug-ins, shipping modules all can know when data needs to be cleared, or has been cleared
* Updated functions to use new clear data function rather than just wp_clear_cache
Nag store admin to check store settings after upgrade
* also adds a general administrator nag class to our repertoire to make future nagging and error reporting that much more fun

Addresses issues #1272 and #1270
Save data immediately when data map is initialized
* also clear dirty flag when saved
removed debug code
Merge pull request #1284 from JeffPyeBrook/pr-1283-saving-and-restoring-datamap-class

Save data immediately when data map is initialized
remember names of transients as they are set so we can clear them specifically
no mass flushing of WordPress cache
handles upgrade automatically by looking at database on first run
spelling corrections in comments
Don't display invalid shipping choices when there is a USPS quote error
* capture error from XML
* save error for next time checkout page is rendered
* output error (using existing action hooks ) into checkout page
* clear saved errors prior to shipping being recalculated

**Note that this is a quick (but reasonable) fix and needs to be expanded on going forward.**
updated since in phpDoc
changed function name
Merge remote-tracking branch 'origin/pr-1259-invalid-zip-codes-usps' into branch-3.8.14.1-dev

Conflicts:
	wpsc-includes/shopping_cart_functions.php
	wpsc-shipping/usps_20.php
Merge branch 'pr-1280-shipping-same-as-billing-change-region-update' into branch-3.8.14.1-dev
Merge remote-tracking branch 'origin/pr-1272-nag-user-to-check-checkout-settings' into branch-3.8.14.1-dev
Merge remote-tracking branch 'origin/pr-1251-clear-temporary-data' into branch-3.8.14.1-dev