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/_docs/11-posts.md

@@ -0,0 +1,37 @@
+---
+title: "Working with Posts"
+permalink: /docs/posts/
+excerpt: "Suggestions and Front Matter defaults for working with posts."
+modified: 2016-11-03T11:12:40-04:00
+---
+
+Posts are stored in the `_posts` directory and named according to the `YEAR-MONTH-DAY-title.MARKUP` format as per [the usual](https://jekyllrb.com/docs/posts/).
+
+Where `YEAR` is a four-digit number, `MONTH` and `DAY` are both two-digit numbers, and `MARKUP` is the file extension representing the format used in the file. For example, the following are examples of valid post filenames:
+
+```
+2016-07-20-writing-jekyll-posts.md
+2015-01-03-static-site-generators.markdown
+```
+
+**Recommended Front Matter Defaults:**
+
+```yaml
+defaults:
+  # _posts
+  - scope:
+      path: ""
+      type: posts
+    values:
+      layout: single
+      author_profile: true
+      read_time: true
+      comments: true
+      share: true
+      related: true
+```
+
+Adding the above to `_config.yml` will assign the `single` layout and enable: *author profile*, *reading time*, *comments*, [*social sharing links*]({{ "/docs/layouts/#social-sharing-links" | absolute_url }}), and *related posts*, for all posts.
+
+**ProTip:** Remember to write unique `excerpt` descriptions for each post for improved SEO and archive listings.
+{: .notice--info}