Locked Jekyll at 2.4.0
Revert "Locked Jekyll at 2.4.0"

This reverts commit 33d40fc9f25ac3227961296bd493ffb4e233c668.
Locked Jekyll at 2.4.0, added html-proofer
Adjusted permalink, added highlighter setting for pygments
Initial Rakefile, currently just has testing for html-proofer
Preparing for continuous integration