Merge branch 'develop' of git.ispconfig.org:ispconfig/ispconfig3 into develop

install/lib/installer_base.lib.php

install/tpl/apache_apps.vhost.master

install/tpl/nginx_apps.vhost.master

interface/web/admin/templates/language_add.htm

interface/web/admin/templates/language_complete.htm

interface/web/admin/templates/language_export.htm

interface/web/admin/templates/language_import.htm

interface/web/admin/templates/remote_action_ispcupdate.htm

interface/web/admin/templates/remote_action_osupdate.htm

interface/web/dns/templates/dns_import.htm

interface/web/dns/templates/dns_wizard.htm

interface/web/mail/templates/mail_user_backup.htm

interface/web/mail/templates/xmpp_domain_edit_ssl.htm

interface/web/sites/templates/web_vhost_domain_advanced.htm

interface/web/sites/templates/web_vhost_domain_backup.htm

interface/web/sites/templates/web_vhost_domain_edit.htm

interface/web/sites/templates/web_vhost_domain_redirect.htm

interface/web/sites/templates/web_vhost_domain_ssl.htm

interface/web/sites/templates/web_vhost_domain_stats.htm

interface/web/tools/templates/import_ispconfig.htm