[Merge] ~medicalwei/livecd-rootfs:feat/oem-extra-make-hooks into livecd-rootfs:ubuntu/master

[Michael Hudson-Doyle]

Review: Approve

Looks like a good start to me.
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https://code.launchpad.net/~medicalwei/livecd-rootfs/+git/livecd-rootfs/+merge/446132
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