server,client: Implement ssl/tls encryption

server,client: Implement ssl/tls encryption

The server and client now use ssl to communicate, with certificates
generated by `cert-server.pl`.

Clients connect to the cert-server to request a certificate using a
password. After receiving a certificate they can connect to the server
and start sending logs.

Rewrote the server in perl to facilitate use of encryption.

Removed use of actually portable perl due to the prebuilt binary not
including IO::Socket::SSL and Net::SSLeay. Rebuilding the perl binary
would be required to use encryption, so the system perl will be used
instead.