When creating a multi-server setup I used a partly copied, partly
symlinked directory structure for the different servers after creating a
certificate for each server with `easyrsa build-server-full`. In that
process I also copied the `server` directory.
The rsync command does not delete files which are not excluded so it
included the correct server key and the original one which can be a
security risk.
* rsync can copy the actual files.
* This change makes it easier to modifier the configuration and sync it
to the server. You only have to execute the ovpn_copy_server_files
once.
