These are ubuntu-isms that do not exist on debian mirrors and cause
builds to break if they're based on a stable debian release.
Change-Id: I08c2826eba4aabd0be69955220624b2f179a15ee
Closes-bug: #1450198
debootstrap is not debian or ubuntu specific. We can make a debootstrap
element that knows how to do all of the things, and then a
debian-minimal and ubuntu-minimal image that use it. Finally, make
the debian element simply be a collection of the extra things we do to
make it look like a cloud-init based cloud image.
Change-Id: Iaf46c8e61bf1cac9a096cbfd75d6d6a9111b701e
