Added french translation files for backend and frontend.

frontend/id/exhibitions.json

@@ -23,6 +23,7 @@
         "tour": "Tour through the exhibition",
         "export_for_calendar": "Export for calendar",
         "permanent_exhibition": "Permanent exhibition",
-        "permanent_exhibition_headline": "permanent exhibition"
+        "permanent_exhibition_headline": "permanent exhibition",
+        "tiles": "Tiles"
     }
 }