[Merge] ~davidkrauser/livecd-rootfs/+git/livecd-rootfs:bootable-buildd into livecd-rootfs:ubuntu/master

[Michał Sawicz]

@David, one other thing I realized is the instances don't shut down when asked. Neither ACPI power event or `halt` inside the instance ultimately result in the system shutting down.

We will forcefully kill the machines after a timeout, but we'd rather it behave.
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https://code.launchpad.net/~davidkrauser/livecd-rootfs/+git/livecd-rootfs/+merge/373916
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~davidkrauser/livecd-rootfs/+git/livecd-rootfs:bootable-buildd into livecd-rootfs:ubuntu/master.