Fix lunch initialization

Change-Id: Ibc5a96ec674614756db15b45150a9358992a3ee4
diff --git a/User.php b/User.php
index 1b459cf..8326033 100644
--- a/User.php
+++ b/User.php
@@ -62,6 +62,9 @@
         $this->vegetarian_dinner = false;
         $this->registered_at = date("Y-m-d H:i:s") . "UTC";
         $this->earlybird_registration = false;
+        $this->lunch_day_1 = "";
+        $this->lunch_day_2 = "";
+        $this->lunch_day_3 = "";
         $this->total_due = 0.0;
         $this->invoice = "";
     }