Allow adding tracking code for webstatistics service. E.g. piwik.

app/views/layouts/_header.html.haml

@@ -8,7 +8,7 @@
     = csrf_meta_tags
     = stylesheet_link_tag "application", :media => "all"
     //%link(href="images/favicon.ico" rel="shortcut icon")
-    
+
     = yield(:head)
     = foodcoop_css_tag
 
@@ -25,3 +25,4 @@
       I18n.locale = "#{I18n.locale}";
       I18n.fallbacks = true;
     = yield(:javascript)
+    = raw FoodsoftConfig[:webstats_tracking_code]

config/app_config.yml.SAMPLE

@@ -123,6 +123,11 @@ default: &defaults
     encoding: utf8
     socket: /opt/lampp/var/mysql/mysql.sock
 
+  # Uncomment to add tracking code for web statistics, e.g. piwik
+  #webstats_tracking_code: |
+  #  <!-- Piwik -->
+  #  ......
+
 development:
   <<: *defaults