Fix wrapper to work with barbicanclient 3.0.1

Due to the updates to the python-barbicanclient in version 3.0.1, the cinder
barbican wrapper no longer functions.  This patch updates the cinder barbican
wrapper and test cases to work with barbicanclient 3.0.1.

Change-Id: Ibef4abd5fd9b12962420eaa5d7ebf62700171861
Closes-Bug: #1388461
(cherry picked from commit 2d52d4177ca7cf41ee8162f07e444d9b75c377dd)
Merge "Fix wrapper to work with barbicanclient 3.0.1" into stable/juno