Implement server kicks and updating the server time on the page according to heartbeats

static/css/main.css

@@ -10,6 +10,10 @@ body {
     font-family: Verdana,Tahoma,"DejaVu Sans",sans-serif;
 }
 
+body.night, body.evening {
+    background-image: url(img/bg_night.png);
+}
+
 .stat-box {
     padding: 1em;
     color: #fff;