[*] MO : mondial relay

fix issues from Prestashop's recommandations
In this [commit](https://github.com/PrestaShop/PrestaShop-modules/commit/8f0da9fd91152171d585a73b41c7f7e468e58563#diff-18aa970ce7692edad49b704785125132R30), I added ```{assign var=MR_Data value=$MR_Data|json_decode:1}``` to send your variables properly to smarty.