more image tweaks

_includes/post.html

@@ -2,7 +2,7 @@
   <header>
     <h1 class="entry-title">{{ post.title }}</h1>
     {% if post.image %}
-      <div class="feature-image" style="background: url({{ post.image }})"></div>
+      <img class="feature-image" src="{{ post.image }}" alt="{{ post.title }}">
     {% endif %}
     <time datetime="{{ post.date | datetime | date_to_xmlschema }}" pubdate><a href="{{ post.url }}">{{ post.date | date: "%B %d, %Y" }}</a></time>
   </header>