Merged revisions 3049-3051,3053-3054,3058,3070,3074-3077,3082,3086-3088,3091-3092,3094-3095 from stable branch.

- Installer adds Apache and nginx user to ispapps group.
- Installer makes sure that /var/www/apps has 755 permissions.

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- Fedora installer: create a symlink from /usr/share/phpmyadmin to /usr/share/phpMyAdmin (nginx only).

- 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.

- Added support for the /etc/nginx/sites-available and /etc/nginx/sites-enabled directories on Fedora/CentOS to the installer.

- replace double-quotes with single-quotes whenever appropriate
- fix indentation

- Added a fix for opensuse regarding issue: FS#1250 - smtp file in pam.d directory on some distributions is world readable.

- Added Installation instructions for Fedora 12
- Added Dovecot support for fedora 12

Fixed a problem with broken tolower function in maildrop when compiled with some specific gcc settings by forcing lowercase addresses in master.cf and adding a workaround in case that tolower returns a empty result.