* Stop explicitly encoding strings we pass to rbd: the library
supports multiple string types now.
* We mock module rbd from rbd_utils.py, also need set module rbd's
specific exceptions with object inherit from BaseException to avoid
TypeError like: 'TypeError: catching classes that do not inherit from
BaseException is not allowed'
Partially-Implements: blueprint goal-python35
Co-Authored-By: Davanum Srinivas <davanum@gmail.com>
Change-Id: I3eec213ad9bc13f0a371a5c4f28d3df377796125