Add includes for static-based comments powered by Staticman

- Configure Staticman with sane defaults
- Build comment form to capture new comments and ajax data to Staticman
- Build comments view that iterates over `_data/comments/post-slug/*.yml` files

_config.yml

@@ -18,7 +18,7 @@ teaser                   : # filename of teaser fallback teaser image placed in
 # breadcrumbs            : false # true, false (default)
 words_per_minute         : 200
 comments:
-  provider               : # false (default), "disqus", "discourse", "facebook", "google-plus", custom"
+  provider               : "staticman" # false (default), "disqus", "discourse", "facebook", "google-plus", "staticman", "custom"
   disqus:
     shortname            : # https://help.disqus.com/customer/portal/articles/466208-what-s-a-shortname-
   discourse:
@@ -28,6 +28,15 @@ comments:
     appid                :
     num_posts            : # 5 (default)
     colorscheme          : # "light" (default), "dark"
+staticman:
+  allowedFields          : ['name', 'email', 'url', 'message']
+  branch                 : # "master", "gh-pages"
+  format                 : "yml"
+  moderation             : true
+  path                   : "_data/comments/{options.slug}"
+  requiredFields         : ['name', 'email', 'message']
+  transforms:
+    email                : "md5"
 atom_feed:
   path                   : # blank (default) uses feed.xml