Use WP_HTTP API in USPS.  Works on servers without curl now.  Nifty.
Update Polish language file
overrideMimeType does not exist in IE, and also, because the headers are set properly in wp_send_json(), this is unnecessary.
Eliminate erroneous debug variable from wp-e-commerce.js.  Introduced in 4409bfa8fbf194cee9dcf477167a96bd3f758fc4