Fixed a small bug in the nav.php which tries to lookup a custom module config file even if no module is selected and  enabled the dashboard module for the admin user by default after installation.

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.

Patch from Filip that enables settting of sys_user.modules and sys_user.startmodule via client_add remote API call

Changed quota setting for courier installations in authmysqlrc.master as ispconfig sets the quota with maildirmake command, so we do not have to specify a sql quota field.

Temporary fix for: FS#1311 - Only first PHPINIDir directive honored per configuration tree - subsequent ones ignored 

Added document_root_www field to the web_domain table. This field contains the symlink path to the website.

Removing white space in the remote_user.tform.php file while calling the client_template_get_by_user function. Reported by ispcomm

- Fix some comments.