Remove variable for custom CSS. If user needs speed then he should use assets plugin

Fix #67

templates/base.html

@@ -31,9 +31,7 @@
         <link rel="stylesheet" type="text/css" href="{{ SITEURL }}/theme/css/pygments.css" media="screen">
         <link rel="stylesheet" type="text/css" href="{{ SITEURL }}/theme/tipuesearch/tipuesearch.css" media="screen">
         <link rel="stylesheet" type="text/css" href="{{ SITEURL }}/theme/css/elegant.css" media="screen">
-            {%if CUSTOM_CSS %}
         <link rel="stylesheet" type="text/css" href="{{ SITEURL }}/theme/css/custom.css" media="screen">
-            {% endif %}
         {% endif %}
         {% endblock head_links %}
         {% include '_includes/favicon_links.html' %}