[Merge] ~utkarsh/livecd-rootfs/+git/livecd-rootfs:use-packaged-unminimize into livecd-rootfs:ubuntu/master

[Utkarsh Gupta]

Thank you, Phil and  Gauthier. Now that I actually think about it, I should merge this before the next ubuntu-server image build is run because:

- unminimize is now seeded.
- which means, unminimize will be installed.
- as soon as it's installed in the image, it'll run `rm -f /usr/local/sbin/unminimize`.
- and then the current code - `yes | /usr/local/sbin/unminimize` will start to fail.

...so before that happens, I'll land this.
-- 
https://code.launchpad.net/~utkarsh/livecd-rootfs/+git/livecd-rootfs/+merge/465177
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