[dashboard] When deleting environment failed, it's impossible to get through failed env

[Victor Ryzhenkin]

The bug was discovered during testing new engine with new yaql.

Steps:
1. Deploy env.
2. Delete env.

If environment removing failed, try to get into environment.

Trace in browser from django:
http://paste.openstack.org/show/412450/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/211350

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/211350
Committed: https://git.openstack.org/cgit/openstack/murano-dashboard/commit/?id=143df725ea324ed626dbc3b92964e0149cea86d9
Submitter: Jenkins
Branch: master

commit 143df725ea324ed626dbc3b92964e0149cea86d9
Author: Kirill Zaitsev <email address hidden>
Date: Tue Aug 11 01:54:00 2015 +0300

    Do not render topology for env with empty services

    Topology rendering code expects services to be an iterable.
    During environment deletion however services can be None.
    This commit makes topology code aware of this fact and prevents any
    further job if environment.services is None.

    Closes-Bug: #1483420

    Change-Id: I2edbd2342c163c6c180c6238fa933c42f94e4d87