You can download different formats from rendered.
You must have ruby installed, tested mostly on 1.9.2+
[sudo] gem install bundler
bundle install
[sudo] gem install redcarpet
All text is in markdown. To build the book, you must install calibre.
Building a PDF is a bit more involved. It requires you have both Pandoc and xelatex (XeTeX for OSX, and MikTeX for Windows) installed.
bookgen.rb
The tools to build the PDF were pilfered from the Pro Git book builder. Thanks to that team.