- Enabled Security Level (Server Config > Web > Security Level) for nginx.

fix #1747 - check for amavised for postfix rules -> pure webserver need for php sendmail, most often postfix is used for it, because admin know it. I checked different repos for differnet names, alwas amavsid or with -new.

- Added UFW firewall support.

*) Forgot to add the entries for mailman in the main.cf of postfix

• Added configure_dovecot function
• Updated functions configure_postfix, configure_pureftpd, configure_apache, install_ispconfig, configure_apps_vhost
• Bug fix in configure_amavis where installer was not including the ispconfig config file
• Bug fix in configure_apache where in suphp.conf the php handler line would be duplicated through updates
• replace double-quoted strings with single-quoted whenever appropriate
• changed inline comments to coding standards
• fixed OS specific paths
• changes to installer_base 1) add_database_server_record added os specific override of awstats paths 2) find_installed_apps courier not detecting correctly for gentoo

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

remove exec() calls, replace /usr/local/ispconfig with variable, replace double-quoted strings with single-quoted whenever appropriate