Update formatting for site update post, clean up some date formatting and set front matter defaults.

_layouts/post.html

@@ -5,7 +5,7 @@ layout: default
 
   <header class="post-header">
     <h1 class="post-title" itemprop="name headline">{{ page.title }}</h1>
-    <p class="post-meta"><time datetime="{{ page.date | date_to_xmlschema }}" itemprop="datePublished">{{ page.date | date: "%b %-d, %Y" }}</time>{% if page.author %} • <span itemprop="author" itemscope itemtype="http://schema.org/Person"><span itemprop="name">{{ page.author }}</span></span>{% endif %}</p>
+    <p class="post-meta"><time datetime="{{ page.date | date_to_xmlschema }}" itemprop="datePublished">{{ page.date | date: "%Y-%m-%d" }}</time>{% if page.author %} • <span itemprop="author" itemscope itemtype="http://schema.org/Person"><span itemprop="name">{{ page.author }}</span></span>{% endif %}</p>
   </header>
 
   <div class="post-content" itemprop="articleBody">