detect the ubuntu version based on /etc/os-release

Uwe Merbeth

2016-05-09 f5daecadf5846ff0b2d512e6a1a47f17342fe02b

 interface/web/mail/mail_user_edit.php

@@ -209,7 +209,7 @@

      // Set Maildir format
      if ($this->id == 0) {
         $this->dataRecord['maildir_format'] = $sys_config['maildir_format'];
         $this->dataRecord['maildir_format'] = $mail_config['maildir_format'];
      }
      else {
         // restore Maildir format