added defaul value to cc field

Author: renky

install/sql/ispconfig3.sql

@@ -1038,7 +1038,7 @@ CREATE TABLE `mail_user` (
   `maildir` varchar(255) NOT NULL default '',
   `maildir_format` varchar(255) NOT NULL default 'maildir',
   `quota` bigint(20) NOT NULL default '-1',
-  `cc` text,
+  `cc` text NOT NULL default '',
   `sender_cc` varchar(255) NOT NULL default '',
   `homedir` varchar(255) NOT NULL default '',
   `autoresponder` enum('n','y') NOT NULL default 'n',