--disk-format option to `openstack image create` fails on older version of python-openstackclient

[Dominique Poulain]

profiles/common includes a call to `openstack image create` like so:

openstack image show $image_name || {
        openstack image create --public \
            --container-format=bare --disk-format=$image_format \
            --file=${HOME}/images/$image_file $image_name \
            --property architecture=$image_arch \
            --property hypervisor_type=$image_hv_type
    }

(lines 22-28; erroring flag option at <http://bazaar.launchpad.net/~ost-maintainers/openstack-charm-testing/trunk/view/head:/profiles/common#L24>).

While --disk-format is valid syntax for python-openstackclient for 2.3.0 on Xenial, that is not the case for version 0.3.0, which is the one available for Trusty, and for which the option is spelt disk_format instead (underscore instead of dash).

Version tables:

$ rmadison python-openstackclient
 python-openstackclient | 0.3.0-1ubuntu1 | trusty/universe | source, all
 python-openstackclient | 1.0.1-0ubuntu1 | vivid/universe | source, all
 python-openstackclient | 1.0.3-0ubuntu1 | vivid-updates/universe | source, all
 python-openstackclient | 1.7.0-1 | wily | source, all
 python-openstackclient | 2.3.0-2 | xenial | source, all
 python-openstackclient | 3.2.0-0ubuntu2 | yakkety | source, all

On a 14.04.5 Trusty box:

$ apt-cache policy python-openstackclient
python-openstackclient:
  Installed: 0.3.0-1ubuntu1
  Candidate: 0.3.0-1ubuntu1
  Version table:
 *** 0.3.0-1ubuntu1 0
        500 http://nova.clouds.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status

As a result, openstack errors out, and the configure script blows up:

+ openstack image create --public --container-format=bare --disk-format=qcow2 --file=/home/ubuntu/images/xenial-server-cloudimg-amd64-disk1.img xenial --property architecture=x86_64 --property hypervisor_type=qemu
INFO: urllib3.connectionpool Starting new HTTP connection (1): <REDACTED>
usage: openstack image create [-h] [-f {shell,table}] [-c COLUMN]
                              [--variable VARIABLE] [--prefix PREFIX]
                              [--disk_format <disk_format>] [--id <id>]
                              [--store <store>]
                              [--container-format <container_format>]
                              [--owner <project>] [--size <size>]
                              [--min-disk <disk_gb>] [--min-ram <disk_ram>]
                              [--location <image_url>] [--file <file>]
                              [--checksum <checksum>]
                              [--copy-from <image_url>]
                              [--property <key=value>]
                              [--protected | --unprotected]
                              [--public | --private]
                              <name>
openstack image create: error: unrecognized arguments: --disk-format=qcow2

Trusty/python-openstackclient 0.3.0:

openstack --version && openstack image create 2>&1 | grep disk_format
openstack 0.3.0
                              [--disk_format <disk_format>] [--id <id>]

As against Xenial/python-openstackclient 2.3.0:

$ openstack --version && openstack image create 2>&1 | grep disk-format
openstack 2.3.0
                              [--disk-format <disk-format>]