Documentation publishing system based on Jekyll

- added a Liquid tag for making tabbed examples with Bootstrap
- added a generator to create a JSON version of each page
Add some documentation to test out the system

- Fix Liquid rendering of JSON version of pages
- Test out having documentation in HTML format
Add sidebars to output
Make a Sinatra app to do post-processing of JSON output

This seems simpler than trying to generate every thing in the JSON
ahead of time.