Description of problem:
If volume has snaphost, it can't be deleted (need to remove them first). If you navigate to detail of the volume, there exists a link to Delete volume - and it shouldn't be there.


Version-Release number of selected component (if applicable):
RHEL 7.2
python-django-horizon-8.0.0-10.el7ost.noarch
openstack-dashboard-theme-8.0.0-10.el7ost.noarch
openstack-dashboard-8.0.0-10.el7ost.noarch
openstack-packstack-puppet-7.0.0-0.11.dev1692.g1b5e83b.el7ost.noarch
openstack-packstack-7.0.0-0.11.dev1692.g1b5e83b.el7ost.noarch

How reproducible:
100%

Steps to Reproduce:
1. log in as demo user
2. Project - Compute - Volumes
3. create Volume with default values, name it "test"
4. verify, that drop down menu of the row with "test" volume contain Delete volume
click to Create snapshot, name it as "test_snap"
navigate back to list of Volumes (not snapshots of them)
verify, that drop down menu of the row with "test" volume does NOT contain Delete volume
click to name of the volume to navigate to detail of volume "test"
on the right top of page there is action button with dropdown menu. There is Delete volume item, that is not accessible from list of volumes


Actual results:
Delete volume item on detail page shouldn't be there, if there exists snapshot of it

Expected results:
Delete volume is visible always (or seems to be)

Additional info: