[Merge] ~mwhudson/livecd-rootfs/+git/livecd-rootfs:desktop-source-catalogs into livecd-rootfs:ubuntu/master

[Michael Hudson-Doyle]

> Oh, just another comment, the update-source-catalog change doesn't seem to
> part of building the desktop catalogs, maybe should be a different commit?

Yes, good point, I'll do that. Thanks for the review!
-- 
https://code.launchpad.net/~mwhudson/livecd-rootfs/+git/livecd-rootfs/+merge/408449
Your team Ubuntu Core Development Team is subscribed to branch livecd-rootfs:ubuntu/master.