Linux: Add support for SPIDEV (#734)

RPi and Linux refactor.

Add GPIO Sysfs for GPIO operations.

Update configure script.

Fix some cppcheck warnings.

Add serial emulation that prints to stdout.

Fix some file headers.

drivers/Linux/EthernetServer.cpp

@@ -5,9 +5,9 @@
  * repeater and gateway builds a routing tables in EEPROM which keeps track of the
  * network topology allowing messages to be routed to nodes.
  *
- * Created by Marcelo Aquino <marceloaqno@gmail.org>
- * Copyright (C) 2016 Marcelo Aquino
- * Full contributor list: https://github.com/mysensors/MySensors/graphs/contributors
+ * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
+ * Copyright (C) 2013-2017 Sensnology AB
+ * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
  *
  * Documentation: http://www.mysensors.org
  * Support Forum: http://forum.mysensors.org
@@ -33,7 +33,7 @@
 #include "EthernetServer.h"
 
 EthernetServer::EthernetServer(uint16_t port, uint16_t max_clients) : port(port),
-	max_clients(max_clients)
+	max_clients(max_clients), sockfd(-1)
 {
 	clients.reserve(max_clients);
 }