Add Fathom tracking snippet

layouts/default.erb

@@ -24,6 +24,21 @@
     <!-- Font Awesome -->
     <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.6.3/css/font-awesome.min.css" integrity="sha384-T8Gy5hrqNKT+hzMclPo118YTQO6cYprQmhrYwIiQ/3axmI1hQomh7Ud2hPOy8SP1" crossorigin="anonymous">
 
+    <!-- Fathom - simple website analytics - https://github.com/usefathom/fathom -->
+    <script>
+    (function(f, a, t, h, o, m){
+      a[h]=a[h]||function(){
+        (a[h].q=a[h].q||[]).push(arguments)
+      };
+      o=f.createElement('script'),
+      m=f.getElementsByTagName('script')[0];
+      o.async=1; o.src=t; o.id='fathom-script';
+      m.parentNode.insertBefore(o,m)
+    })(document, window, '//stats.zeus.gent/tracker.js', 'fathom');
+    fathom('trackPageview');
+    </script>
+    <!-- / Fathom -->
+
     <%= content_for(@item, :head) %>
   </head>