Port libnm-core/libnm to GDBus.
The NetworkManager daemon continues to use dbus-glib; the
previously-added connection hash/variant conversion methods are now
moved to NetworkManagerUtils (along with a few other utilities that
are now only needed by the daemon code).
This commit implements MAC cloning feature in NetworkManager. To support that,
'PermHwAddress' property is added into *.Device.Wired and *.Device.Wireless
interfaces. The permanent MAC address is obtained when creating the device, and
is used for 'locking' connections to the device. If a cloned MAC is specified
in connection to be activated, the MAC is set to the interface in stage1. While
disconecting, the permanent MAC is set back to the interface.
