use ESM, add server setup, cleanup

Change-Id: Iafac35c2082523ae98c31017d9bad5c4d6e18ef3
diff --git a/model/Conversation.js b/model/Conversation.js
index 22dc477..09fb76f 100644
--- a/model/Conversation.js
+++ b/model/Conversation.js
@@ -1,4 +1,4 @@
-const Contact = require('./Contact')
+import Contact from './Contact.js'
 
 class Conversation {
     constructor(id, accountId, members) {
@@ -62,4 +62,4 @@
     }
 }
 
-module.exports = Conversation;
+export default Conversation;