Added support for the "Redirect" tab to nginx.

install/tpl/nginx_ispconfig.vhost.master

interface/web/sites/form/web_aliasdomain.tform.php

interface/web/sites/form/web_domain.tform.php

interface/web/sites/form/web_subdomain.tform.php

interface/web/sites/templates/web_aliasdomain_edit.htm

interface/web/sites/templates/web_domain_advanced.htm

interface/web/sites/templates/web_domain_redirect.htm

interface/web/sites/templates/web_subdomain_edit.htm

server/conf/nginx_vhost.conf.master

server/plugins-available/nginx_plugin.inc.php