Keep nfv

I added both `:close()` and `:reconfig()` methods to Intel10g (had to fix a little on app.lua for the second one).

The `:close()` is still missing deallocations, but the `:reconfig()` works on the "diff_vlans => same_vlan" test.
These waits make me nervous because they "stop the world" and I am not sure how long it can take to wait for e.g. `TDH==TDT`. Can we minimize waiting? I would prefer the risk of dropping packets to the risk of blocking for a nontrivial length of time.