Deprecate API v2 (#7761)

* deprecate api-v2

* remove v2 test helpers

* remove unused string

website/server/middlewares/response.js

@@ -0,0 +1,28 @@
+module.exports = function responseHandler (req, res, next) {
+  // Only used for successful responses
+  res.respond = function respond (status = 200, data = {}, message) {
+    let user = res.locals && res.locals.user;
+
+    let response = {
+      success: status < 400,
+      data,
+    };
+
+    if (message) response.message = message;
+
+    // When userV=Number (user version) query parameter is passed and a user is logged in,
+    // sends back the current user._v in the response so that the client
+    // can verify if it's the most up to date data.
+    // Considered part of the private API for now and not officially supported
+    if (user) {
+      response.notifications = user.notifications.map(notification => notification.toJSON());
+      if (req.query.userV) {
+        response.userV = user._v;
+      }
+    }
+
+    res.status(status).json(response);
+  };
+
+  next();
+};