everything: use libgudev instead of HAL; merge NM and nm-system-settings

The only thing that doesn't work yet is the system-settings service's
"auto eth" connections for ethernet devices that don't have an existing
connection.  Might also have issues with unmanaged devices that can't
provide a MAC address until they are brought up, but we'll see.

system-settings/plugins/ifupdown/interface_parser.c

@@ -22,7 +22,6 @@
 
 
 #include "interface_parser.h"
-#include "NetworkManagerUtils.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>