[enh] new favicon added

searx/templates/base.html

     <meta name="viewport" content="width=device-width, maximum-scale=1.0, user-scalable=1" />
     <title>{% block title %}{% endblock %}searx</title>
     <link rel="stylesheet" href="/static/css/style.css" type="text/css" media="screen" />
-    <link rel="shortcut icon" href="{{ url_for('static', filename='img/favicon.png') }}" />
+    <link rel="shortcut icon" href="{{ url_for('static', filename='img/favicon.png') }}?v=2" />
     {% block styles %}
     {% endblock %}
     {% block head %}