Bugfix: $app->system->unlink function had wrong parameter name, no files were deleted ever

- Added overtraffic notifications to traffic quota system (part of FS#2059 - Extend Traffic quota system)

- Added missing sys_tpl table to ispconfig3.sql and moved the definition of the table to the upd_0035.sql file as new tables cant be added in existing update files.
- added new ssl_key field to web_domain table.
- cleaned up unused code from apache plugin.

- Added new web folder named private to web folder layout. The folder is intended to store data that shall not be visible in the web directory, it is owned by the user of the web.
- Changed ownership of web root directory to root user in all security modes to prevent symlink attacks.
- Apache log files are now owned by user root.
- Improved functions in system library.

- Fixed: FS#2292 - monitor_tools.inc.php uses /var/vmail and not the mail directory specified in server config
- Changed code comment in login/index.php file.

Added wrappers for several base filesystem functions like rename, copy, chown, chgrp etc. to system lib.

This option can be enabled under System > Server config and is named "Web folder protection".

Implemented: FS#560 - Add support for APS (Application Packaging Standard)

Implemented: FS#2131 - skip network reconfigure requests on mirror servers that are for a different server_id

- Added "actions" framework in server to replace the functions provided by the core modules
- Moved system update function from remoteactins core module to software update plugin.

and make changes to mysql users in the mysql plugin module.

Refs: 1722

Also removed the calls to the db closeConn calls in favor of
destryong the connections on the class __destruct() 's..

Since firebird db had a closeConn as well, changed its __destruct
to calls its own personal closeConn which otherwise left unmodified.

Refs: 1722

Fixed: FS#1775 - PHP Fatal error: Call to a member function queryAllRecords() on a non-object in /usr/local/ispconfi

Fixed: FS#1709 - Wrong message "Your hard-disk space is going full" in the "Monitor -> Show Disk Usage"

Fixed: FS#1623 - vhost.conf.master placed in /root overrides vhost.conf.master in ispconfig/server/conf