[IMP] add collaboration capabilities

Author: Emilien Durieu (edu)

dev/index.html

@@ -125,7 +125,9 @@
 
         <!-- add mocha -->
         <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/mocha/3.2.0/mocha.css">
+        <script src="https://cdn.socket.io/3.1.3/socket.io.min.js" integrity="sha384-cPwlPLvBTa3sKAgddT6krw0cJat7egBga3DJepJyrLl4Q9/5WLra3rrnMcyTyOnh" crossorigin="anonymous"></script>
         <script src="https://cdnjs.cloudflare.com/ajax/libs/mocha/3.2.0/mocha.js"></script>
+        <script src="https://cdnjs.cloudflare.com/ajax/libs/sinon.js/10.0.0/sinon.min.js"></script>
         <script>
             mocha.setup('bdd');
         </script>