Disconnect not being detected

[TomMettam]

Running as a server.

In the case where the remote client disappears (i.e, the connection doesn't get explicitly closed) the SSE client remains active indefinitely, with no disconnect events being fired.

To reproduce:

1. Start an SSE server using this module.
2. Connect to the eventsource from a mobile device (I used an android tablet)
3. After connecting, turn off WiFi
4. Observe that even after the tcp_keepalive_time has expired, and even after sending regular "keepalive" packets to the client, the connection never registers as dropped, resulting in a leak.

[psturm51]

In the file, sseclient.js, in SSEClient constructor, you will see a line hooking the res (responses) close event to the close event. This should be changed to the req (request) close event:

req.on('close',function(){
self.emit("close");
});