Implemented:  FS#2422 - Use domain module when creating subdomains 
Bugfix: datalog was used in the wrong way on editing aliasdomains
Bugfix: missing datalog update for parent domain on editing subdomains

Bugfix: Show error message on smtp enabled without administrator mail / name

- Fixed missing templates and language entries
- Previous subdomain mode can be used concurrently
- Changed log path to a more convenient location

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 new module called "domain". With this module you can manage all domains (web + mail). Per default this module is not active. To activate it, you have to change the System Interface Config -> domains -> use the domain module. You also have to activate the domain-module for the admin (and for every client if you want). Important: you can not use this module if you have reseller!

- Formatted error messages for better visibility.

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

- Fixed several bugs.