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/_sass/vendor/font-awesome/_font-awesome.scss

@@ -0,0 +1,18 @@
+/*!
+ *  Font Awesome 4.6.3 by @davegandy - http://fontawesome.io - @fontawesome
+ *  License - http://fontawesome.io/license (Font: SIL OFL 1.1, CSS: MIT License)
+ */
+
+@import "variables";
+@import "mixins";
+@import "path";
+@import "core";
+@import "larger";
+@import "fixed-width";
+@import "list";
+@import "bordered-pulled";
+@import "animated";
+@import "rotated-flipped";
+@import "stacked";
+@import "icons";
+@import "screen-reader";