I integrated JSTree to display the list of post categories in the sidebar.

I integrated the JSTree control into the website. I created the
categories.json data file to define the tree structure data for the
JSTree control.
I refactored the blog to fix issues with the Jekyll update for GitHub Pages.

GitHub upgraded their Jekyll implementation to 1.0. There were
significant differences in the page generation from the previous
version of Jekyll. I refactored the website to fix the rendering issues.