Fix query_cluster_vols_for_ssc(): cast string (records) to int. On
Python 3, comparison between str and int now raise a TypeError.
tox.ini: add cinder.tests.unit.test_netapp_ssc to Python 3.4.
Partial-Implements: blueprint cinder-python3
Change-Id: I05127340029a5bb6c8444f51341be8008aab8dc8