stress/actions/ssh_floating.py n-net compatibility

ssh_floating.py did not worked with nova network because of the
used security group specification style.

Now it is expected to work regardless neutron or n-net used for
networking.

Change-Id: I14000e97fb6a857c7c0fed126a90e7e16509d8ec
Move verification of response attributes into service client

Moves the verification of service/volume response body attributes to
the service client rather than in each test which uses the service
client.

Partially implements blueprint nova-api-attribute-test

Change-Id: Ie829e2beb1e065a2804dab93835c3d1933fd419d
Merge "stress/actions/ssh_floating.py n-net compatibility"
Merge "Move verification of response attributes into service client"
Merge branch 'master' of https://github.com/openstack/tempest