Add NetApp CopyOffload tests.

This commit adds the NetApp copyoffload automated tests.  It also
adds some utility files, and refactors the devstack_utils to be more
pythonic and remove unnecessary code.  The devstack_utils used by
tempest does not need to be invoked from command line,
so that code was removed.

Change-Id: Id176e864e447bce4693b53697ea651893775ad8c