RIPD-108:  Use a self-signed certificate for peers

Nano-quibble: too uniform spacing makes it hard to distinguish what's going on.
Consider grouping like this:

    evp_pkey_ptr pkey = evp_pkey_new();
    evp_pkey_assign_rsa (pkey.get(), rsa_generate_key (2048));

    x509_ptr cert = x509_new();
    x509_set_pubkey (cert.get(), pkey.get());
    x509_sign (cert.get(), pkey.get());

    SSL_CTX* const ctx = m_context.native_handle();
    ssl_ctx_use_certificate (ctx, cert);
    ssl_ctx_use_privatekey  (ctx, pkey);