Charts translation

1) Allow in settings tab to translate hard coded strings in ~plugin/dist/js/index.js eg. : line 4702 : text: "Views / Visitors / Sessions", line 20920 : numberFormat: "Views: #", etc... 2) set chart's locale with WP locale =>impact on labels and popups remark : don't work adding in index.js line 20940 : ], "language": "fr"