Fixes a namespace issue in RegisterController, a=chris

diff --git a/src/controllers/RegisterController.php b/src/controllers/RegisterController.php
index 996073b36..afebdf2bb 100755
--- a/src/controllers/RegisterController.php
+++ b/src/controllers/RegisterController.php
@@ -31,6 +31,7 @@
 namespace seekquarry\yioop\controllers;

 use seekquarry\yioop\configs as C;
+use seekquarry\yioop\library as L;
 use seekquarry\yioop\library\CrawlConstants;
 use seekquarry\yioop\library\MailServer;
 use seekquarry\yioop\models\LocaleModel;