use setInterval rather than setTimeout, cosmetic fixes

nsupdate/main/templates/main/update.html

@@ -50,11 +50,10 @@
         .fail(function( data ) {
             $('#response').text('myip failed');
         });
-        setTimeout('checkIP', 300000);  // repeat in N ms
     }
 
     $(document).ready(function() {
-        checkIP();
+        setInterval(checkIP, 300000);  // repeat every N ms
     });
     </script>
 {% endblock %}