Handle subscription of messages in the webapp.

Messages larger than a threshold are split and reassembled due to the
size limit in webrtc. Threshold may have to be adjusted somewhere between
64KiB and 256KiB.

This also includes a basic handler for a ping message and a more
advanced image handler.

Change-Id: If66acfb1bb84e9d3ff686994a94b1480cb70b2aa
diff --git a/y2020/www/index.html b/y2020/www/index.html
new file mode 100644
index 0000000..97e16d4
--- /dev/null
+++ b/y2020/www/index.html
@@ -0,0 +1,11 @@
+<html>
+  <head>
+    <script src="flatbuffers.js"></script>
+    <script src="main_bundle.min.js" defer></script>
+    <link rel="stylesheet" href="styles.css">
+  </head>
+  <body>
+    <div id="config">
+    </div>
+  </body>
+</html>