About to allow dht to start without local addresses. this is
so that we can initialize the dht and sign it up to listen
on the muxer, before our node starts accepting incoming connections.
otherwise, we lose some (we're observing this happening already).

I looked through the dht's use of the peerstore, and the check here
doesnt seem to be as important as the panic implies. I believe the
panic was used for debugging weird "dont have any address" conditions
we had earlier.