Stack preview fails validation

[andersonvom]

stack-preview doesn't follow the regular flow of a stack creation or create the specific resources. Therefore certain validations do not apply at preview time (such as validating a certain property exists that is retrieved from a resource attribute. e.g. the string from a OS::Heat::RandomString).
Validation of nested stacks should be removed.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/134343

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/134343
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=1bb039d8477615493889912f91992c612cf2deec
Submitter: Jenkins
Branch: master

commit 1bb039d8477615493889912f91992c612cf2deec
Author: Anderson Mesquita <email address hidden>
Date: Thu Nov 13 14:39:34 2014 -0500

    Remove validation of nested stack for preview

    At preview time, resources have not been created and certain validation
    do not apply (such as validating properties acquired from other
    resources attributes), so this patch removes the validation of nested
    stacks.

    Closes-Bug: 1392455
    Change-Id: I39be064c775369f1180487f4b48184e288734c49