* swarm: completed 1st phase of swap accounting * swarm: swap accounting for swarm with p2p accounting * swarm/swap: addressed PR comments * swarm/swap: ignore ErrNotFound on stateStore.Get() * swarm/swap: GetPeerBalance test; add TODO for chequebook API check * swarm/network/stream: fix NewRegistry calls with new arguments * swarm/swap: address @justelad's PR comments