add tracking code to 404 page

static/404.html

@@ -47,5 +47,17 @@
       <h1>Well, this is embarassing... &#x1F633;</h1>
       <p>The specified file was not found on this website. Please check the URL for mistakes and try again, or <a href="/">go home</a>.</p>
     </div>
+    <script>
+      var _paq = _paq || [];
+      _paq.push(['trackPageView']);
+      _paq.push(['enableLinkTracking']);
+      (function() {
+        var u="https://stats.jarv.is/";
+        _paq.push(['setTrackerUrl', u+'m.php']);
+        _paq.push(['setSiteId', '1']);
+        var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
+        g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'m.js'; s.parentNode.insertBefore(g,s);
+      })();
+    </script>
   </body>
 </html>