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

test/_pages/page-b.md

@@ -0,0 +1,7 @@
+---
+title: "Page B"
+permalink: /page-b/
+date: 2011-06-23T18:39:14+00:00
+---
+
+(lorem ipsum)