Adds Plausibile script into IPFS 404 page, above redirect. (#315)

* Adds special Plausible function to enable 404 tracking.

* Adds script and logic for 404 tracking in Plausible.

* Adds 404 logic to IPFS side of things.

* Moves the 404 notifier above the refresh.

* Removes duplicate script.

Author: johnnymatthews

static/ipfs-404.html

@@ -5,7 +5,7 @@
     <link rel="canonical" href="https://lotus.filecoin.io/"/>
     <meta name="robots" content="noindex">
     <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
+    <script>plausible("404",{ props: { path: document.location.pathname } });</script>
     <meta http-equiv="refresh" content="0; url=https://lotus.filecoin.io/"/>
   </head>
-  <script>plausible("404",{ props: { path: document.location.pathname } });</script>
 </html>