refactor: use old verify method

Do not use the brand new, recommended by the docs, way of verifying your
certificate. Instead use the old way because older clients give error
when they process the config.

template/client.ovpn.tmpl

@@ -5,13 +5,13 @@ dev tun
 proto udp
 remote {{ .Hostname }} {{ .Port }}
 resolv-retry infinite
-remote-cert-tls server
 ns-cert-type server
 nobind
 persist-key
 persist-tun
 comp-lzo
 verb 3
+auth-nocache
 
 <ca>
 {{ .CA }}</ca>