Fix openSUSE cloud image download and extraction

Use the latest available version of the rootfs (instead of a qcow2
image) to simplify rootfs extraction.

Change-Id: Ic3a646b923738464b5217d799758b6980b2deaf2
Handle non-existing *generic kernel and initrd

Finding the Debian boot kernel and initrd is collapsed into a
single statement so that the script doesn't bail out when
'set -o pipefail' is set and the *generic kernel and initrd are
absent.

Change-Id: Ifd616818f7387e6f102636c7cf186be6097f1d5c
Closes-Bug: 1335016
Move dpkg manifest creation to finalise

As some finalise steps can install packages we need to generate the
dpkg manifest after that has occurred.

Change-Id: I2177db2e64d4d9c21deeac7cf017919888a2d524
Install openstack-selinux on RHEL

The openstack-selinux package contains policy updates for OpenStack.
Updates are accrued in openstack-selinux before they are merged into
the upstream selinux-policy package.

Change-Id: I7c00e5cae17489202fe7aee3e656fca27ab630ba
Add unit test for cache-url

A sanity check that cache-url does the right thing when presented
with the appropriate curl return codes.  This change brings in the
test code for scripts from tripleo-image-elements, which needs to
be factored out into a place both projects can use it.

I'm stubbing out curl so we don't have a dep on curl in our unit
tests, and because I've seen some strange behavior out of curl in
the gate that caused random failures in this test.

Change-Id: I31e6b06b45415feec7285511d07e65eb78d0d045
Fix $DISTRO_NAME usage for centos7 element

In both of the changed files in this patch, the $DISTRO_NAME usage
is checking against "centos".  The valid value for the centos7
element for $DISTRO_NAME is "centos7"[1].

[1] http://git.io/8IvuTw

Change-Id: I0c4a4b2ecf87c7a9283d10071f6feb494a6c716a
Update EPEL release rpm

EPEL 7 was released September 30. The beta release rpm was removed
from the repo and was replaced with the final release rpm.

Change-Id: I103a2f7abd7563869b9e39ccc1fbb3cfbd9ff6ae
Merge "Fix $DISTRO_NAME usage for centos7 element"
Ensure epel7 is installed only on rhel7/centos7

Change-Id: I5812812f7d2cb5ba2e310e33d6e01cda8823c1c4
Merge "Add unit test for cache-url"
Merge "Install openstack-selinux on RHEL"
Save extended attributes when creating tar

The way redhat-common's extract-image script was creating the base
tarball caused file capabilities to get dropped, which meant that
things like ping in RHEL 7 images was unusable for regular users.
This change adds the necessary options to the tar call to maintain
as many extended attributes as possible.

--acls and --selinux are intentionally omitted, and the selinux
xattrs are filtered out because all of those items cause issues
in our chroot environment.  We restore selinux attributes at the
end of the build anyway so that shouldn't be a problem.

bz reference: https://bugzilla.redhat.com/show_bug.cgi?id=1144149

Change-Id: Ibff99ce9bde01bc5ecf95dc3a5d3e2cebe5015b9
Use DIB_IMAGE_CACHE everywhere

disk-image-create processes a DIB_IMAGE_CACHE variable and exports it,
but there are several elements that ignore the value and wrote out
the base location themselves. Use the variable everywhere so that it
will get overridden everywhere.

Change-Id: I00fff354d6c931ad67cf3052d055f0e4604dfdc8
Merge "Fix openSUSE cloud image download and extraction"
Merge "Save extended attributes when creating tar"
Merge "Move dpkg manifest creation to finalise"
Merge "Ensure epel7 is installed only on rhel7/centos7"
Do not try to detach non-existant loopback devices

A user reported symptoms where the losetup line used to detach the
loopback device was failing in tar mode. We don't need to detach a
device that does not exist.

Change-Id: I807996e16199288927b49b4f300ae9b461cb8fe7
Closes-Bug: #1378033
Merge "Do not try to detach non-existant loopback devices"
Merge "Handle non-existing *generic kernel and initrd"