Fix author meta

Author: matklad

_layouts/post.html

@@ -4,7 +4,7 @@
 <article>
 <h1>{{ page.title }}</h1>
 <div class="post-meta sect1">
-  {{ page.author}}, {{ page.date | date: "%b %-d, %Y" }}
+  {% if page.author %}{{ page.author}}, {% endif %}{{ page.date | date: "%b %-d, %Y" }}
 </div>
 {{ content }}
 </article>