addedit.php: add 0.5 as old_version

setup.php

@@ -77,6 +77,7 @@ class CSetupInvoice extends w2p_Core_Setup
 	public function upgrade($old_version) {
                 switch ($old_version) {
                 case 0.1:
+                case 0.5:
                 default:
                     return true;
                 }