Fixed: FS#2378 - $conf['theme'] value in interface/lib/config.inc.php is overwritten (reset to 'default') on update

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

- Improved support for multiple PHP versions. Additional PHP versions have now their own form and database table.

- 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.

replaced "listen ... ssl;" through "ssl on;" in nginx (ispconfig.vhost) in case that ssl is used for ispconfig

Cleaned and shortened to be more manageable.  There is no reason to keep all that luggage. Also use multi line sql so a human can read it.

- Changed FastCGI buffers for ISPConfig nginx vhost because otherwise you get "upstream sent too big header while reading response header from upstream" on OpenSUSE.
- Added 502 error page ("Bad Gateway").
- Added "fastcgi_intercept_errors on;" to nginx vhost template so that ISPConfig's error pages are displayed instead of the default nginx ones.

- Removed ufw configuration from installer to avoid "PHP Notice:  Undefined index: ufw in /tmp/trunk/install/install.php on line 251".
- Changed phpMyAdmin location in ISPConfig nginx vhost to allow phpmyadmin and phpmyadmin/ (with and without trailing slash).

- Installer adds ispconfig user to Apache group on Fedora/CentOS so that nginx/PHP-FPM can access /etc/squirrelmail and serve SquirrelMail for the ISPConfig vhost.
- Added session.save_path and upload_tmp_dir settings to the PHP-FPM pool definitions.

Changed PHP-FPM socket directory from /var/run/php5-fpm to /var/lib/php5-fpm because /var/run is cleand up on reboot.

- Added SNI config field in sysetm > server config > web.