Fix: sometimes there is no back button in app

Vocaluxe/Website/index.html

@@ -78,7 +78,7 @@
     </div>
     <!-- /page -->
 
-    <div id="main" data-role="page" data-content-theme="a">
+    <div id="main" data-role="page" data-content-theme="a" data-add-back-btn="false">
         <div data-role="header">
             <h1>Volcaluxe</h1>
         </div>