Don't add author blurb if not present

_layouts/post.html

@@ -43,12 +43,14 @@
 
           <hr />
 
+          {% if site.author_blurb %}
           <div class="author row">
             <img class="col-xs-4 col-sm-3 col-md-2" src="{{site.baseurl}}{{site.author_blurb_image}}" alt="Me" />
             <p class="col-xs-8 col-sm-9 col-md-10">
               {{ site.author_blurb }}
             </p>
           </div>
+          {% endif%}
         </div>
       </div>
     </section>