Not informative error message while making package public if package with the same FQPN already public by other tenant

[Victor Ryzhenkin]

Steps:
1. Log into horizon.
2. Upload murano-app(Apache, for example)
3. Make this app public
4. Change tenant.
5. Upload the same app.
6. Try to make app public

Actual:
Error: Unable to toggle public: Apache HTTP Server

Expected:
Correct reason, why user can't make app public

[Kirill Zaitsev (kzaitsev)]

There seem to be 2 cases: 1) another package with such fqn is already public 2) not enough permissions.

[Lin Yang (lin-a-yang)]

For the first case, when another package with such fqn is already public, API will return correct message like below.

"Class with the same full name is already registered in the visibility scope"

But dashboard didn't show this message back to user.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/235786

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/235786
Committed: https://git.openstack.org/cgit/openstack/murano-dashboard/commit/?id=a4c7558519e4f9f8fa41f67225e195bbf3e10045
Submitter: Jenkins
Branch: master

commit a4c7558519e4f9f8fa41f67225e195bbf3e10045
Author: Lin Yang <email address hidden>
Date: Fri Oct 16 16:44:28 2015 +0800

    Improve message for publish package conflict

    When user publish a package conflict with another public package with same FQN,
    API server will throw webob.exc.HTTPConflict. So catch the exception on
    dashboard and give back a specific reason to user.

    Change-Id: I3cd7ea24c6645487e6c7155a1f530c64f31bd332
    Closes-Bug: #1475079
    Co-authored-by: zhu.rong <[e-mail]>