Added the configuration variable $conf['demo_mode'] in the config.inc.php file. It disables the newly introduced demo mode which limits certain actions in the interface part of ispconfig: the demo mode can be used to run the ispconfig interface part as online demo.

Added a Checkbox to the language import form to ignore the version of the language file.

- Added dutch translation (many thanks to Hans!)

- Changed shell of website linux user to /bin/false