Add support for login & logout while keeping the same shared worker

www/common/cryptpad-common.js

@@ -932,9 +932,12 @@ define([
                     document.location.reload();
                 } else if (o && !n) {
                     LocalStore.logout();
-                    postMessage("DISCONNECT");
                 }
             });
+            LocalStore.onLogout(function () {
+                console.log('onLogout: disconnect');
+                postMessage("DISCONNECT");
+            });
 
             if (PINNING_ENABLED && LocalStore.isLoggedIn()) {
                 console.log("logged in. pads will be pinned");