Don't re-install cloud-init for centos7 images

The centos7 images come with the base version of cloud-init already
installed.

---
$ virt-inspector CentOS-7-x86_64-GenericCloud-GA-7.0.1406_01.qcow2
...
      <application>
        <name>cloud-init</name>
        <version>0.7.5</version>
        <release>10.el7.centos.1</release>
        <arch>x86_64</arch>
      </application>
...
---

I think this is a hang-over from early rhel7 images that didn't have
it.

Change-Id: Idf488942222d9e6bca4d66f04f5af42e6707944d
Preserve exit value when leaving cleanup trap

If we entered the cleanup trap due to exit with an error code we should
exit dib with an error code.

Change-Id: Iee1a05668b3239113fb91a2da0d9a66d7de4db6b
Echo that qemu-img convert is running

qemu-img convert can take a few minutes to complete, or far longer
on heavily loaded systems. Notify the user that the image is
undergoing conversion to save them just seeing END PROFILING.

Change-Id: I1ad61ce5ed011b721d48e2d12fb42ef4aa5cd1f6
Allow for multiple image outputs from raw source

When uploading images to multiple clouds it is possible that the same
image will be needed in multiple formats to accomodate hypervisors
across clouds. Update disk-image-create's -t flag to take a list of
desired output image formats so that a single disk-image-create can
output all of the desired image formats.

Change-Id: If121b2342ae888855ba435aa3189f039e985b812
Consolidate lsb_release source-repositories

Each distro had its own copy of the file, but they were all the
same and it's actually installed in redhat-common so it belongs
there.

Change-Id: Iad15f39fd28d1c4e20d30dcb2eb0ae6f2fa2b015
Merge "Preserve exit value when leaving cleanup trap"
Move to final release of CentOS7 images

This is the final released image; it is the same one deployed in many
cloud provers such as HP and AWS.  It is also safe from all known
vulnerabilities up to its release

Change-Id: Ib8ba561662d2a98da55eb292b850dc019226dd59
Force empty $TMPDIR inside the chroot

There are some situations (use of libpam-tmpdir) where the $TMPDIR is
defined per user, so any sudo call will define an specific $TMPDIR for
the root user which doesn't exist inside the chroot.

Change-Id: I866651fed520007506c7be83837d3791ed9f2235
Closes-Bug: #1330290
Remove first-boot.d support

After being deprecated two releases ago, finally remove any reference
for the support of first-boot.d

Change-Id: I08d67404ef48cad61db3b18fb86e970abfa5d2b6
Merge "Don't re-install cloud-init for centos7 images"
Merge "Remove first-boot.d support"
Merge "Force empty $TMPDIR inside the chroot"
Merge "Consolidate lsb_release source-repositories"
Merge "Allow for multiple image outputs from raw source"
iso element to build bootable ISO images

This commit adds a new element named 'iso' to build a bootable
ISO image for the kernel/ramdisk emitted by the 'baremetal' or
'ramdisk' element.

Change-Id: I89d175a29e2d0bc64b47fe527f0d0f6875f6849a