Move gh-pages branch files into /docs and add test files

- Jekyll ignore `/docs` and `/test` folders when using from root
- Update Staticman config to point to correct branch and data file location
- Replace `{{ base_path }}` references with `absolute_url` filter
- Update documentation

docs/_posts/2012-03-15-layout-author-sidebar-disabled.md

@@ -0,0 +1,9 @@
+---
+title: "Layout: Author Sidebar Disabled"
+excerpt: "A post to test disabling author sidebar."
+author_profile: false
+---
+
+This post has the author sidebar disabled.
+
+To disable add `author_profile: false` to YAML Front Matter.