nd_light: make app reconfigurable
nd_light: make app reconfigurable

Add a reconfig() method.  This is primarily used to set the local MAC
address, which is only available until after any interface drivers
have been initialized.

dpino/snabb,Igalia/snabbswitch,dpino/snabb,dpino/snabbswitch,snabbco/snabb,dpino/snabbswitch,snabbco/snabb,snabbco/snabb,eugeneia/snabb,Igalia/snabb,Igalia/snabbswitch,dpino/snabb,SnabbCo/snabbswitch,SnabbCo/snabbswitch,Igalia/snabb,dpino/snabbswitch,eugeneia/snabb,SnabbCo/snabbswitch,Igalia/snabb,alexandergall/snabbswitch,alexandergall/snabbswitch,snabbco/snabb,eugeneia/snabb,alexandergall/snabbswitch,dpino/snabbswitch,Igalia/snabb,eugeneia/snabb,Igalia/snabbswitch,dpino/snabb,alexandergall/snabbswitch,dpino/snabb,snabbco/snabb,eugeneia/snabbswitch,dpino/snabb,eugeneia/snabb,eugeneia/snabbswitch,Igalia/snabb,SnabbCo/snabbswitch,alexandergall/snabbswitch,Igalia/snabb,eugeneia/snabb,Igalia/snabbswitch,snabbco/snabb,Igalia/snabb,dpino/snabb,alexandergall/snabbswitch,eugeneia/snabbswitch,eugeneia/snabb,Igalia/snabb,snabbco/snabb,eugeneia/snabbswitch,alexandergall/snabbswitch,Igalia/snabbswitch,alexandergall/snabbswitch,eugeneia/snabb,snabbco/snabb