Jupyter index files not found (path spaces)

Should panelcode enforce the avoidance of spaces in path names in order to work around problems like this one, currently inhibiting viewing of HTML output via a Docker / Jupyter Notebooks deployment?

- https://github.com/jupyter/docker-stacks/pull/473

From Maite:
### Index Not Found

> When I try to view the output index for 99 Ways or Understanding Comics, I get a 404 message that says, “Not Found. You are requesting a page that does not exist.” If I view an individual image, this does not happen. Only if I try to view the whole index. I’m not sure if this is some sort of interference from the thumbnails.