Fix translations

Translation files in www/wp-content/plugins/civicrm/civicrm/ext/com.drastikbydesign.stripe/l10n/fr_FR/LC_MESSAGES were not used at all.

The civicrm wiki (https://wiki.civicrm.org/confluence/pages/viewpage.action?pageId=295108824) doesn't indicate that addScriptUrl bypass the string localization but i think it actualy does :)