Updated the Debian installation instructions.

Moved server modules and plugins to new directory and updated the installer to create the symlinks for the modules and plugins from *-available to *-enabled directory.
Fixed a typo in mailfilter template.

Added a server module for clients and a mail plugin.

2.) Cleaned up update.php
3.) Changed definitions for quarantine settings
4.) Commented out areas for quarantining 'clean' and 'other' 

2.) included missing configurations in config.inc.php.master
3.) disabled header & ini_set for shell actions in config.inc.php.master

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