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

index.html

@@ -6,9 +6,9 @@ layout: default
   {% if last_meta.active %}
     <div class="site-update">
       Site Update:
-      <a href="{{ last_meta.href | prepend: site.baseurl }}">
+      <a href="{{ last_meta.url | prepend: site.baseurl }}">
         {{ last_meta.title }}
-      </a>
+      </a> ({{ last_meta.date | date: "%Y-%m-%d" }})
     </div>
   {% endif %}