Making incoming connection <-> peer association world class

[Raynos]

Currently the way we associate incoming connections with the correct peer on the root channel is by reaching into the channel when we finish the init handshake for incoming connections.

See https://github.com/uber/tchannel-node/blob/master/connection.js#L466-L482

TChannelConnection.prototype.onInIdentified = function onInIdentified(init) {
    var self = this;
    if (init.hostPort === '0.0.0.0:0') {
        self.ephemeral = true;
        self.remoteName = '' + self.socket.remoteAddress + ':' + self.socket.remotePort;
        assert(self.remoteName !== self.channel.hostPort,
              'should not be able to receive ephemeral connection from self');
    } else {
        self.remoteName = init.hostPort;
    }

    self.channel.peers.add(self.remoteName).addConnection(self);
    self.identifiedEvent.emit(self, {
        hostPort: self.remoteName,
        processName: init.processName
    });
};

Note that there is a horrible bug here where we completely ignore the peer.draining and peer.closing state and just blindly addConnection.

Either we should check the state here or make addConnection more world class.

[jcorbin]

I'd argue for the practical:

• if draining, drain this new connection (if direction match in the peer draining case, chan draining is always)
• if peer closing: no connection for you, close it