Removed quotes from domain field in mysql-virtual_domains.cf.master

Author: tbrehm

install/tpl/mysql-virtual_domains.cf.master

@@ -2,7 +2,7 @@ user = {mysql_server_ispconfig_user}
 password = {mysql_server_ispconfig_password}
 dbname = {mysql_server_database}
 table = mail_domain
-select_field = 'domain'
+select_field = domain
 where_field = domain
 additional_conditions = and server_id = {server_id}
 hosts = {mysql_server_ip}