[IIAB] gutenberg files

[Joel Steres]

Hi Braddock,

> I am also mirroring cache/generated - the gutenberg mirrors seem to block
> access to it via ftp etc, but I can get it via rsync. Maybe those files will
> be more consistent.

Thanks for mirroring cache/generated. In the current catalog all files
referencing 'cache' point to cache/epub/... rather than
cache/generated/ and the contents of the two paths differ. I looked at
the rsync script from git but it does not seem to include the addition
for gutenberg.org/cache mirroring.  Could you either make the
adjustment or show me where to do so?

Also, I found that html files include images.  It might be easier to
put the gutenberg files into the flask static directory and permit the
existing paths to work.  No objections if I symlink to
/knowledge/data/gutenberg/gutenberg/ from iiab/static/gutenberg/data/?

-Joel