Watch chequebounced events and take action

[Eknir]

https://github.com/ethersphere/swarm/issues/1885 prevents a node from sending cheques that can be bounced. This issue is about the action which a node takes when the smart-contract of a peer emits a ChequeBounced event.

The proposed action is to disconnect.

To complete this issue, we will have to set up event-watchers for ChequeBounced events and take the appropriate action when an event fires.

[Eknir]

@ralph-pichler , what is the computational load of setting up an event-watcher per peer?

[ralph-pichler]

With the current go bindings this is only possible using eth_Subscribe over websockets, but RSK does not implement that yet.

[holisticode]

We need the blacklist for this. Postponed but needs to be implemented before main net launch.