Default Article Settings

Need to implement metalsmith-default-values for the articles, defaulting the following settings:

layout: articles/article-page.pug
categories: ["general"]
author: Git username of who first committed the article (not exactly sure how this should be done yet, since metalsmith-default-values only takes strings, objects and arrays, so no callback that interacts with Githubs API can be done... yet!)

it-from-bit / metalsmith-geekwiki.io