* CLDC-2863: rename maintenance_mode_enabled? to service_unavailable?
* CLDC-2863: update 'maintenance' to 'service unavailable' in tests
* CLDC-2863: rename check_maintenance to check_maintenance_status
* CLDC-2863: implement service_moved functionality
* CLDC-2863: add tests for service_moved functionality
* CLDC-2863: add tests for when both feature toggles are on
* CLDC-2863: remove full stop from service moved page title
* CLDC-2863: turn on service moved feature
* CLDC-2863: turn off service moved feature
* CLDC-2862: first attempt at creating maintenance page
* CLDC-2907: try turning off maintenance mode to see if tests pass
* CLDC-2862: write tests for MaintenanceController
* CLDC-2862: test header bar links hidden in maintenance mode
* CLDC-2862: lint
* CLDC-2862: add requests tests
* CLDC-2862: try disabling schduled job in maintenance mode
* CLDC-2862: turn on maintenance mode temporarily
* CLDC-2862: turn off maintenance mode again
* CLDC-2862: ensure cookies, notices etc still available in maintenance mode
* CLDC-2862: update content on maintenance page
* CLDC-2862: destroy sidekiq cron jobs on shutdown
* CLDC-2862: turn maintenance mode back on
* CLDC-2862: try destroying cron jobs on startup
* CLDC-2862: try destroying cron jobs on shutdown again, but with fix
* CLDC-2862: turn maintenance mode off again
* CLDC-2862: move job destruction to sidekiq server startup
* CLDC-2862: turn MM back on
* CLDC-2862: turn MM off again
* CLDC-2862: update 'contact the helpdesk' content
* CLDC-2862: check notices/statements still viewable in MM
* CLDC-2862: check cookies page still viewable in MM
* CLDC-2862: confirm cookie banner visible regardless of MM
* CLDC-2862: reenable MM
* CLDC-2862: turn maintenance mode off again