Deprecate API v2 (#7761)

* deprecate api-v2

* remove v2 test helpers

* remove unused string

website/server/libs/csvStringify.js

@@ -0,0 +1,11 @@
+import csvStringify from 'csv-stringify';
+import Bluebird from 'bluebird';
+
+module.exports = (input) => {
+  return new Bluebird((resolve, reject) => {
+    csvStringify(input, (err, output) => {
+      if (err) return reject(err);
+      return resolve(output);
+    });
+  });
+};