[DIB] Use of $IMAGE_TYPE not consistent with base diskimage-builder project

[Chad Roberts]

In the sahara-image-elements/diskimage-create/diskimage-create.sh script, we take the -i argument and use that as IMAGE_TYPE. In our case, we are referring to the OS of the base image being used. However, in the diskimage-builder project, $IMAGE_TYPE refers to the type of image being created (currently, .qcow2 or .tar).

In order to reduce the chance for confusion and to be more precise in our source code, we should probably change $IMAGE_TYPE to something like BASE_IMAGE_OS or DISTRO_NAME (which is used in the base project) since it is more descriptive and is not conflicting with other uses.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/126568

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/126568
Committed: https://git.openstack.org/cgit/openstack/sahara-image-elements/commit/?id=bbed50ca815025a44792f343bd6c9c6847b2db02
Submitter: Jenkins
Branch: master

commit bbed50ca815025a44792f343bd6c9c6847b2db02
Author: Chad Roberts <email address hidden>
Date: Tue Oct 7 10:26:33 2014 -0400

    Refactoring IMAGE_TYPE to BASE_IMAGE_OS

    Using IMAGE_TYPE to reflect the OS of the base image
    conflicts with the way that the diskimage-builder project
    uses IMAGE_TYPE (qcow2 vs tar) and was confusing.
    We are now using BASE_IMAGE_OS since it properly
    reflects what we are using it for and does not conflict
    with the diskimage-builder project.

    Change-Id: I9e84077c1bc9b8890076838e34a157cb7a3884db
    Closes-Bug: #1378364