- forcing browser to refresh images via timestamp

app/templates/personal.html

@@ -4,10 +4,10 @@
 	<h1> Statistik </h1>
 	<div>
 	<h2> Bierkonsum </h2>
-	<img src="{{ url_for('static', filename='total.png') }}">
+	<img src="{{ url_for('static', filename='total.png') }}?{{timestamp}}">
 	{% if user %}
         {% set fils = "total%03d.png" % user.id %}
-    	<img src="{{ url_for('static', filename=fils) }}">
+    	<img src="{{ url_for('static', filename=fils) }}?{{timestamp}}">
 	{% endif %}
 	</div>
 	<h1> Abrechnung </h1>