add commas to tags

example/content/1948-12-12-the-purpose-of-education.md

@@ -3,7 +3,7 @@ layout: post
 cover: 'assets/images/cover5.jpg'
 title: The Purpose of Education
 date: 1948-12-12 10:18:00
-tags: speeches fiction
+tags: speeches, fiction
 subclass: 'post tag-speeches'
 kind: writing
 public: true

example/content/2014-08-12-the-businessman-and-fisherman.md

@@ -3,7 +3,7 @@ layout: post
 cover: 'assets/images/cover7.jpg'
 title: The Businessman & the fisherman
 date:   2014-08-12 10:18:00
-tags: fables fiction
+tags: fables, fiction
 subclass: 'post tag-test tag-content'
 categories: 'casper'
 kind: writing