[Merge] ~rs2009/ubuntu-release-upgrader:add-ubuntu-unity into ubuntu-release-upgrader:ubuntu/main

[Nick Rosbrook]

Thanks for this. I have cherry-picked your commit into another MP we have open to make it easier to upload: https://code.launchpad.net/~enr0n/ubuntu-release-upgrader/+git/ubuntu-release-upgrader/+merge/437751.
-- 
https://code.launchpad.net/~rs2009/ubuntu-release-upgrader/+git/ubuntu-release-upgrader/+merge/437647
Your team Ubuntu Core Development Team is subscribed to branch ubuntu-release-upgrader:ubuntu/main.