[*] MO : mondial relay

fix issues from Prestashop's recommandations
On this [commit](https://github.com/PrestaShop/PrestaShop-modules/commit/8f0da9fd91152171d585a73b41c7f7e468e58563#diff-e93c4022df7ea0a04e770aa38e4e51d3R659), I replaced this line because nothing was returned by ```.parent().parent();``` with the default theme on PS 1.6

For more information about the problems we met, you can look at this [page](http://www.prestashop.com/forums/topic/317311-bug-module-mondial-relay/)