[API v3] Maintenance Mode (#7367)

* WIP(maintenance): maintenance

* WIP(maintenance): working locale features

* fix(maintenance): don't translate info page target

* WIP(maintenance): start adding info page

* fix(maintenance): linting

* feat: Add container to maintenance info page

* fix(maintenance): add config.json edits
Also DRY variables for main vs info pages

* fix(maintenance): linting

* refactor(maintenance): further slim down variables

* refactor: Remove unnecessary variables

* fix: Correct string interpolation in maintenace view

* feat: Dynamically add time to maintenance pages

* maintenance mode: do not connect to mongodb

* fix(maintenance): clean up timezones etc.

* fix(maintenance): remove unneeded sprite

test/helpers/api-unit.helper.js

@@ -25,6 +25,7 @@ export function generateGroup (options = {}) {
 
 export function generateRes (options = {}) {
   let defaultRes = {
+    render: sandbox.stub(),
     send: sandbox.stub(),
     status: sandbox.stub().returnsThis(),
     sendStatus: sandbox.stub().returnsThis(),