xfce4-netload-plugin: initial add 1.0.0

* patch taken from xfce-bugzilla [1]
* run tested with wlan0 on overo

[1] https://bugzilla.xfce.org/show_bug.cgi?id=7083



Signed-off-by: Andreas Müller <schnitzeltony@gmx.de>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>