Port violin driver to Python 3

Port violin driver to Python 3

* Replace dict.items()[0] with list(dict.items())[0], same for
  dict.values()
* Replace dict.iteritems() with dict.items()
* Replace dict.itervalues() with dict.values()
* Replace a/b with a//b to get integer on Python 3.
* test_get_active_fc_targets(): ignore order when comparing active
  FC targets. On Python 3, the hash function is randomized and so
  dictionaries values are returned in a random order.

Partial-Implements: blueprint cinder-python3
Change-Id: If2c50606ae68b7f645bfdbe5aaf7510a512e709a