* swarm: completed 1st phase of swap accounting

* swarm, p2p/protocols: added stream pricing

* swarm/network/stream: gofmt simplify stream.go

* swarm: fixed review comments

* swarm: used snapshots for swap tests

* swarm: custom retrieve for swap (less cascaded requests at any one time)

* swarm: addressed PR comments

* swarm: log output formatting

* swarm: removed parallelism in swap tests

* swarm: swap tests simplification

* swarm: removed swap_test.go

* swarm/network/stream: added prefix space for comments

* swarm/network/stream: unit test for prices

* swarm/network/stream: don't hardcode price

* swarm/network/stream: fixed invalid price check