support for better twitter inlcudes

_includes/twittercard.html

+<meta name="twitter:card" content="summary_large_image">
+<meta name="twitter:site" content="@chaotikum_ev">
+<meta name="twitter:title" content="{{ page.title }}">
+
+<meta name="twitter:description"
+    content="{{ page.content | strip_html | xml_escape
+      | truncate: 200 }}">
+
+{% if page.feature_image %}
+  <meta name="twitter:image"
+    content="{{ page.feature_image}}">
+{% else %}
+  <meta name="twitter:image"
+    content="{{site.url}}/{{site.baseurl}}{{ site.default-feature }}">
+{% endif %}

_layouts/post.html

@@ -4,6 +4,8 @@ layout: default
 
 {% include site-header.html %}
 
+{% include twittercard.html %}
+
 <main class="main  container">
 
 	<article class="article  article--post  blogpost content  typeset">