Update UKBA/UKVI launch dates
Update archive date for offdocs to final TNA scrape
Merge pull request #496 from rjc123/newmappings

Update archive date for offdocs to final TNA scrape
Configure dasa.mod.uk on transition-sites
Merge pull request #497 from rjc123/newsites

Configure dasa.mod.uk on transition-sites
Tweak the new homepage for Life in the UK Test

Fran/Till agreed that the guide is better than the transaction start page.
Update the UKBA/UKVI switchover date
Resolve zendesk ticket to unpublish business link assets https://govuk.zendesk.com/tickets/542756