Reverted SVN trunk back to revision 3938 to remove changes in default theme an a replacement of the ispconfig logo.

- Added backup size to web backups

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.

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- Remove of the file how not exists in master language
- Fix the msg show when no file has been created, removed or modified

- Not show line of added string if string added is 0
- If no files has been created or modified show rispective message

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