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/_layouts/archive-taxonomy.html

@@ -0,0 +1,15 @@
+---
+layout: default
+author_profile: false
+---
+
+<div id="main" role="main">
+  {% include sidebar.html %}
+
+  <div class="archive">
+    <h1 class="page__title">{{ page.title }}</h1>
+    {% for post in page.posts %}
+      {% include archive-single.html %}
+    {% endfor %}
+  </div>
+</div>