Resolve "Migrate to Symfony framework"

Closes #28 (closed)

assets/js/now-playing.js

 var lastFetchedNowPlayingData = "";
 
 function updateNowPlaying() {
-    var apiUrl = "now-playing?api";
+    var apiUrl = "now-playing/data";
 
     var newContent = fetch(apiUrl)
         .then(function (response) {
@@ -80,5 +80,7 @@ function buildNowPlayingBlock(apiResponse) {
     return html;
 }
 
-updateNowPlaying();
-setInterval(updateNowPlaying, 2000);
+if (document.getElementById("now-playing")) {
+    updateNowPlaying();
+    setInterval(updateNowPlaying, 3000);
+}