Adapt knowledge base utility script to operate from this project.

[grosscol]

The existing ruby script, https://github.com/Display-Lab/knowledge-base/blob/master/utils/generate_doc.rb, reads from psdo, cpo, and knowledge base to emit a human interpretable form of each causal pathway.

• Copy this utility to this project into a directory that is excluded from jekyll processing.
• Adapt to download ontologies to a temp location, if they're not already present there.
• Adapt to read from slowmo
• Adapt to emit markdown that can be used in the Examples section of the knowledgebase/#causalpathways section of the site.

Addresses #7