Redundant code in stack preview and stack create operations

[Unmesh Gurjar]

The operations performed by heat engine for stack preview is a proper subset of those performed for stack create. The code block for these operations (refer [1] and [2] below) is repeated in the engine service.

This code redundancy can be avoided.

[1] - https://github.com/openstack/heat/blob/master/heat/engine/service.py#L515 to line 523.
[2] - https://github.com/openstack/heat/blob/master/heat/engine/service.py#L559 to line 568.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/104772

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/104772
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=964c4d563abc9da577740bb953fcbf1ec88918ad
Submitter: Jenkins
Branch: master

commit 964c4d563abc9da577740bb953fcbf1ec88918ad
Author: Unmesh Gurjar <email address hidden>
Date: Thu Jul 3 23:04:49 2014 -0700

    Removed redundant code in stack preview, create.

    The operations performed for stack preview is a proper subset of
    those performed for stack create, but the code is repeated.
    Avoided the redundancy by creating a method and having it called
    from preview_stack and create_stack methods.

    Change-Id: I53d9f10913fcb49aa3fdb841b1fc893b8e401e4d
    Closes-Bug: #1337718