wip: Support Fluentd Forward Protocol for TLS

[okkez]

[okkez]

Is this good approach?

@okumin

[okumin]

@okkez I have an approximate approach in a local machine. My approach abstracts a TCP channel.

abstract TcpChannel {
  boolean read();
  boolean write();
}
class TlsPlaintextChannel extends TcpChannel {
…… // implements a normal socket processing
}
class TlsTcpChannel extends TcpChannel {
…… // implements a secure socket processing
}

I have non-strong confidence abount this approach, so let me think for a shot time.