Handle non-ascii category SLUGs correctly

http://open-tools.net/forum/shipping-by-rules-for-woocommerce/5393-rule-evaluate_for_categories-for-non-english-words.html

The Categories variable is printed as: [categories] => Array ( [0] => %cf%80%ce%bd%ce%b5%cf%85 )

• Check if we need to do some utf-8 decoding?
• Does this also apply to all other lists?
• Does this also apply to address fields? => NO, address fields are fine