Cleanup of the node-id.h files. The node-id.h file contains

declarations of functions for setting and getting a node ID number, a
functionality that exists on many platforms. Since this functionality
was not considered part of the Contiki core, each platform defined its
own node-id.h file. This commit attempts to clean this up by
collecting the node-id.h into a core/sys/node-id.h file that replaces
the old node-id.h files from the platform directories.

apps/deluge/deluge.c

@@ -46,7 +46,7 @@
 #include "loader/elfloader.h"
 #include "lib/crc16.h"
 #include "lib/random.h"
-#include "node-id.h"
+#include "sys/node-id.h"
 #include "deluge.h"
 
 #if NETSIM

apps/rest-common/static-routing.c

@@ -24,7 +24,7 @@
 
 #if !UIP_CONF_IPV6_RPL
 #include "contiki-net.h"
-#include "node-id.h"
+#include "sys/node-id.h"
 
 void set_global_address(void)
 {

apps/shell/shell-sky.c

@@ -52,7 +52,7 @@
 #include "dev/sht11-sensor.h"
 #include "net/rime/timesynch.h"
 
-#include "node-id.h"
+#include "sys/node-id.h"
 
 #include <stdio.h>
 #include <string.h>