Fix volume slider touch on mobile devices

Author: debugger22

app/index.html

@@ -33,6 +33,7 @@
     <link rel="stylesheet" href="/static/public/css/main.css"/>
     <script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
     <script src="//cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"></script>
+    <script type="text/javascript" src="//cdnjs.cloudflare.com/ajax/libs/jqueryui-touch-punch/0.2.3/jquery.ui.touch-punch.min.js"></script>
     <script src="//cdnjs.cloudflare.com/ajax/libs/howler/2.0.0/howler.min.js"></script>
     <script src="//cdnjs.cloudflare.com/ajax/libs/socket.io/1.4.8/socket.io.min.js"></script>
     <script src="//cdn.jsdelivr.net/odometer/0.4.7/odometer.min.js"></script>