webui: delete LESS cache only if necessery

one/templates/base.html

@@ -13,7 +13,7 @@
     <script src="{% static "script/jquery.min.js" %}"></script>
     <script type="text/javascript" src="{% url django.views.i18n.javascript_catalog %}"></script>
     <script type="text/javascript">
-        window.localStorage.removeItem('https://cloud.ik.bme.hu/static/style/style.less:timestamp');
+        {% if DEBUG %}window.localStorage.removeItem('https://cloud.ik.bme.hu/static/style/style.less:timestamp');{% endif %}
         var current_user={{user.id}};
     </script>
     {% if DEBUG %}<script src="{% static "script/less.min.js" %}"></script>{% endif %}