[Feature] Basic Staticman Support
Basically a port of Minimal Mistakes's Staticman support to this project, with minor modifications.
Demo site: https://vincenttam.gitlab.io/gl-jekyll/ (source)
P.S. This resolves #18 since Minimal Mistakes, the original source of the Staticman support, adopts the MIT license. Consequently, I have to adopt it for this MR.
Edited by Vincent Tam