removing IP-address autodetection, Tor integration

[David Stainton]

> I think per-server connection preferences should be exposed via the
> introducerless mode which you (Brian) mostly implemented long ago but left
> commented out and which David made work in the truckee branch[1]. Speaking of
> which, I really need to bring that up to date with the last 6 months or so of
> Tahoe development... I'll try to work on that in the near future.

Yes that's right! Brian has already implemented this feature which I
also would like to use. We can easily change it to be an override
table so that none of the storage server options are required... and
the ones specified act as overrides to the introducer acquired storage
server info.