Add rake task to update sponsoring organisations
Add rake task to update sponsoring organisations

This adds a rake task to update all Worldwide Organisations' sponsoring
organisation from FCO to FCDO.

This is part of the work around the Machinery of Government changes that
will see FCO and DFID merge to become a new department.

Trello card: https://trello.com/c/yBvz6SbU/2095-spike-updating-worldwide-organisation-sponsoring-organisations-automatically-to-a-new-org-replace-fco-with-fcdo

alphagov/whitehall,alphagov/whitehall,alphagov/whitehall,alphagov/whitehall