Distribute language code with the app

aleksis/core/static/js/vue/app.js

@@ -64,6 +64,7 @@ const app = new Vue({
         django: window.django,
         // FIXME: maybe just use window.django in every component or find a suitable way to access this property everywhere
         showCacheAlert: false,
+        languageCode: JSON.parse(document.getElementById("current-language").textContent),
     }),
     components: {
         "cache-notification": CacheNotification,