Config nationalcollege.org.uk to match go-live plan

The transition is to use the GOV.UK transition tool to archive an old site, while keeping the namespace alive to be used with a new site at /cms/ 

Type of URL | Expected Result
----------------- | ---------------------
[Homepage](http://www.nationalcollege.org.uk/) | To remain live, pointing at new host, self served
[New CMS URLs](http://www.nationalcollege.org.uk/cms/something) | To point at new host, with self served page
[Previous site URLs](http://www.nationalcollege.org.uk/index/resources/leadingschools.htm) | To resolve to GDS transition tool, likely archived
[All other URLs](http://www.nationalcollege.org.uk/foo/bar) | To point at GDS transition tool, resolving as 404

*Note: these URLS haven't been confirmed by DfE at the time of writing, they may be incorrect - will edit if so*