Handle For Possible New Configuration Data

Handle for possible new configuration data in the future. Use
`repair.config.php` by default, then overwrite the value with the
current configuration data. So, if someday I want to add some new field
in the configuration page, then there will be no error ocurred if user
decide to install new Mecha but keep for using the old configuration
file. Because I can just add the new value in `repair.config.php` as
default value to prevent error of unavailable configuration item.