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/_pages/page-archive.html

@@ -0,0 +1,11 @@
+---
+layout: archive
+title: "Page Archive"
+permalink: /page-archive/
+author_profile: false
+---
+
+{% include base_path %}
+{% for post in site.pages %}
+  {% include archive-single.html %}
+{% endfor %}