Introduced Piwik as an optional plugin

Change-Id: I57d6961ac9e922e1a661ea94a5a6c7563688ed0b
diff --git a/templates/layouts/main.html.ep b/templates/layouts/main.html.ep
index 5f9983c..88c364d 100644
--- a/templates/layouts/main.html.ep
+++ b/templates/layouts/main.html.ep
@@ -81,6 +81,7 @@
       %= include 'partial/footer'
     % };
     %= notifications 'Kalamar::Plugin::Notifications'
-    %= piwik_tag
+
   </body>
+  %= content_block 'scripts'
 </html>