Update NetApp Drivers to use netapp_lib

Update NetApp Drivers to use netapp_lib

Like other vendors, NetApp has published a storage controller
client library to PyPI for use by its OpenStack drivers. This
patch updates the NetApp Cinder drivers to use the new library.

The new library, when downloaded from PyPI, provides the REST
and ZAPI interface code that the driver references.
This code was previously part of the driver code tree in
Cinder: netapp/dataontap/client/api.py and netapp/eseries/client.py.
This patchset removes the relevant code from these files
and also modifies the unit tests to work in the absence
of the new library.

Implements: blueprint netapp-use-pypi-client-library

Change-Id: If51c13ade0497c8e89b044bebb393b52da62029a