Fix UTF-8 error in Prestashop One Page Checkout module

Hello, hereby an overview of the issue: 1) upgraded Prestashop from 1.6.0.9 to 1.6.1.4. This shop is using a multistore feature (Shop1 & Shop2). 2) in Shop2 there are all world's countries / states enabled (using special characters) 3) after the Presta upgrade, One Page Checkout modules do not work in Shop2 (tested with 3 different OPC modules - same issue for all). In Shop1 OPC module works fine. 4) before the Presta upgrade there were no problems 5) according to a specialist the issue is caused by the character encoding error Thank you!