lua_ssl_trusted_certificate
语法: lua_ssl_trusted_certificate
默认: no
环境: http, server, location
指定一个 PEM 格式信任 CA 证书文件，在tcpsock:sslhandshake方法里验证 SSL/TLS 服务的证书
CentOS 6 的路径是 /etc/pki/tls/certs/ca-bundle.crt
要先 $ yum install ca-certificates, 然后 update-ca-trust
其它系统请参考下面的链接
参考链接：
https://manuals.gfi.com/en/kerio/connect/content/server-configuration/ssl-certificates/adding-trusted-root-certificates-to-the-server-1605.html
https://techjourney.net/update-add-ca-certificates-bundle-in-redhat-centos/
http://blog.kankanan.com/article/4fee590d-ssl-certificate-problem-unable-to-get-local-issuer-certificate.html