This patch improves and fixes the documentation of the clone_image
driver method and updates the parameters in various places where the
method is declared where they presented the wrong parameters.
Since there is a valid default implementation for the method, a small
text has been added to indicate that some of the core methods, like this
one, are optional.
To avoid getting docstrings from the driver and the interface (which is
the one used for the documentation) out of sync we replace the
description on cinder/volume/driver.py with a text referencing the
interface docstring.
Change-Id: I09a8357e15b9041790285ab1f9a3cdd7a18243b4
e071ee2632