OpenVPN current release has bad TLS config

[OnGle]

OpenVPN server config, and our openvpn-addclient script both have bad TLS config that will not allow modern openvpn clients to connect.

Specific issue: openvpn 2.5+ does not support AES-256-CBC, we should now be using AES-256-GCM

Workaround:

echo -e 'cipher AES-256-GCM\nauth SHA512' >> /etc/openvpn/server.conf
sed 's/cipher .*/cipher AES-256-GCM/' /usr/local/bin/openvpn-addclient
sed 's/auth .*/auth SHA512/' /usr/local/bin/openvpn-addclient