Added session timeouts.

The parameter 'connection_timeout' for services takes a value as seconds.
All sessions that have been idle for longer than this will be disconnected.

server/modules/protocol/telnetd.c

@@ -156,6 +156,9 @@ char		*password, *t;
 
 	if ((n = dcb_read(dcb, &head)) != -1)
 	{
+	    
+	dcb->last_read = hkheartbeat;
+	
 		if (head)
 		{
 			unsigned char *ptr = GWBUF_DATA(head);