[api] environments GET returns 500 if supplied with a non-existant session_id

[Kirill Zaitsev]

No session check is made during show API call, therefore supplying a non-existant id results in a 500 error.

Expected result a 404 error.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/208671

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/208671
Committed: https://git.openstack.org/cgit/openstack/murano/commit/?id=b2b224ce481721d6dd0ef22b6841c719ec758cd2
Submitter: Jenkins
Branch: master

commit b2b224ce481721d6dd0ef22b6841c719ec758cd2
Author: Kirill Zaitsev <email address hidden>
Date: Tue Aug 4 01:25:26 2015 +0300

    Check session validity during env show api call

    Moves the session check to utils file, together with check_env and
    applies the check during environment show API call, thus raising correct
    errors in case supplied session id is invalid or belongs to a different
    environment

    Change-Id: Ic10956b604cfc7243f07774e9da11caaf18794cd
    Closes-Bug: #1481099