perf(requests): remove font awesome

BREAKING CHANGE: We have removed font awesome. Now we use svg images for all icons. This will result
in one less web request, which in turn will improve your websites performance.

fix #487

templates/base.html

@@ -34,7 +34,6 @@
         <title>{% block title %}{{ SITENAME|striptags|e }}{% endblock title %}</title>
         {% block head_links %}
         <link href="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3.2/css/bootstrap-combined.min.css" rel="stylesheet">
-        <link href="//netdna.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.css" rel="stylesheet">
         {% if 'assets' in PLUGINS %}
         {% include '_includes/minify_css.html' with context %}
         {% else %}