[Merge] ~allenab/livecd-rootfs:CPC-8951-minimal-imagecraft into livecd-rootfs:ubuntu/master

[Allen Abraham]

Hi, thanks for the reviews. The addition of user/pass in the MP was an oversight, apologies. I am looking to fix that while trying to resolve the issue of booting the image on OVH/Openstack.
With regards to the change in implementation and usage of IMAGEFORMAT, I will discuss this with the team and check the viability of such a flow
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https://code.launchpad.net/~allenab/livecd-rootfs/+git/livecd-rootfs/+merge/497451
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