Misleading error message when specifying a wrong update policy

[Thomas Herve]

This is really due to our poor testing, but I realized that if you specify like in our tests "UpdatePolicy": "foo": {}, you get a validatio error "Unknown Property: foo". This is because update_policy is a Properties object, but the message should be customized to be understandable.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/127150
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=3ad4614276ff460cd8d034216c078577f148160e
Submitter: Jenkins
Branch: master

commit 3ad4614276ff460cd8d034216c078577f148160e
Author: Peter Razumovsky <email address hidden>
Date: Wed Oct 8 19:19:13 2014 +0400

    Improve StackValidationFailed response in properties

    In some cases, there is no information about resource and
    section, where Property error raised. This patch improves
    StackValidationFailed msg, so this msg look like "Property
    error : resource_name.section_name.key_name: error_msg", where
    section_name is section, where Property error raised, e.g.
    'update_policy'.

    Change-Id: Iab2a6acdec254b39983de420ab03f994cff48d89
    Closes-bug: #1358512

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/kilo
Review: https://review.openstack.org/195850

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/195850
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=c0d1b9168d7c11a57877d0e9b37eb106d75e2d0a
Submitter: Jenkins
Branch: stable/kilo

commit c0d1b9168d7c11a57877d0e9b37eb106d75e2d0a
Author: Peter Razumovsky <email address hidden>
Date: Wed Oct 8 19:19:13 2014 +0400

    Improve StackValidationFailed response in properties

    In some cases, there is no information about resource and
    section, where Property error raised. This patch improves
    StackValidationFailed msg, so this msg look like "Property
    error : resource_name.section_name.key_name: error_msg", where
    section_name is section, where Property error raised, e.g.
    'update_policy'.

    Cherry-picked from 3ad4614276ff460cd8d034216c078577f148160e
    Change-Id: Iab2a6acdec254b39983de420ab03f994cff48d89
    Closes-bug: #1358512