Remove redundant head-extra block from head.html

Fixes #248 - thanks to @linuxsoftware for the report.

bakerydemo/templates/includes/head.html

@@ -42,7 +42,4 @@
         <script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
         <script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script>
     <![endif]-->
-    
-    {% block head-extra %}
-    {% endblock head-extra %}
 </head>