Add VAT ID to invoice

Change-Id: I0ca3745e6da1008fa5fe9756847c22f44ccc568e
diff --git a/invoice.php b/invoice.php
index d0beef2..8d57898 100644
--- a/invoice.php
+++ b/invoice.php
@@ -76,6 +76,8 @@
 Commerzbank Mannheim
 
 Reference: ICLC-10-" . $user->id . "
+
+VAT ID: DE 143 845 359
 ");
     //$invoice->setFooterNote("xx");