Add support for OpenStack volumes
Fix an editor derp in the magic comment

Clearly, someone derped at one point with their editor on top of
the warning about the magic imports, and then that derpage has been
copied willy-nilly across all of the OpenStack things. This doesn't
have a functional impact, but since it's telling people where to
look for better understanding of magic, it should point to the
right place.
Add volume information into nova inventory