Bump protocol from version 8 to version 9

refs: atom/teletype-client#57 (comment)

Author: jasonrudolph

Diff for: lib/controller-layer.js

@@ -18,7 +18,7 @@ module.exports = ({modelLayer, pubSubGateway, identityProvider, fetchICEServers,
 
   app.get('/protocol-version', function (req, res) {
     res.set('Cache-Control', 'no-store')
-    res.send({version: 8})
+    res.send({version: 9})
   })
 
   app.get('/ice-servers', async function (req, res) {