user_name -> username

Change-Id: I2cb601f7e0eeb36a27e9dad662f3554a0092ab18
diff --git a/index.php b/index.php
index cfc1785..b019079 100755
--- a/index.php
+++ b/index.php
@@ -130,7 +130,7 @@
     $password = $_POST["password"];
     $error = "";
 
-    $error .= validate_username($user->user_name);
+    $error .= validate_username($user->username);
     $error .= validate_name($user->name, $FIRST_NAME_VALIDATION_ERROR);
     $error .= validate_name($user->last_name, $LAST_NAME_VALIDATION_ERROR);
     $error .= validate_email($user->email);
@@ -147,7 +147,7 @@
 
 function backup_user_in_session($user)
 {
-    $_SESSION['username'] = $user->user_name;
+    $_SESSION['username'] = $user->username;
     $_SESSION['first_name'] = $user->first_name;
     $_SESSION['last_name'] = $user->last_name;
     $_SESSION['email'] = $user->email;