Remove barely used tagline variable

_layouts/post.html

@@ -25,7 +25,6 @@
   <article>
     <div class="headline-wrap">
       <h1>{{ page.title }}</h1>
-      <h2>{{ page.tagline }}</h2>
     </div><!--/ .headline-wrap -->
     <div class="article-wrap">
       {{ content }}