Add perex support

_layouts/home.html

@@ -10,10 +10,7 @@ layout: default
         <h1 class="catalogue-title">{{ post.title }}</h1>
         <div class="catalogue-line"></div>
 
-        <p>
-          <!-- sadly this template is not compatible with post.excerpt -->
-          {{ post.content | strip_html | truncatewords: 30 }}
-        </p>
+        <p>{% if post.perex -%}{{ post.perex }}{% else -%}{{ post.content | strip_html | truncatewords: 30 }}{% endif -%}</p>
 
       </div>
     </a>