Reimplementing the website on GitHub Pages

[jobchong]

As part of documentation, this issue describes a shift back to github pages from legalese.readme.io. There are several tasks involved:

• [x] Exporting the documentation content from readme in Markdown: https://dash.readme.io/legacy/project/legalese/v1.0/settings
• [x] Extracting CSS and assets from readme - this now lives in /assets.
• [x] Implementing a jekyll deployment in a github.io repository - documentation now resides at https://github.com/legalese/legalese.github.io#www
• [x] Pointing keycdn to legalese.github.io