Release version 3.3.1

Quick fix release to restore backend.

Author: PowerKiKi

ext_emconf.php

@@ -4,7 +4,7 @@
     'title' => 'Newsletter',
     'description' => 'Send any pages as Newsletter and provide statistics on opened emails and clicked links.',
     'category' => 'module',
-    'version' => '3.3.0',
+    'version' => '3.3.1',
     'state' => 'stable',
     'uploadfolder' => 1,
     'author' => 'Ecodev',