The API only sets 'active' for active interfaces, so it is either 1 or
missing. As 1 compares neither greater nor less than undefined, sorting
by the 'Active' column kept the previous order. The same applies to the
'Autostart' and 'VLAN aware' columns.
Declare those fields as booleans, so that missing values get converted
to false and the interfaces can be sorted by them. The shown values do
not change, as missing values were already rendered as 'No'.
Signed-off-by: Michal Fox <me@dualfroz.com>