ensure event subscriptions work as intended

[noot]

currently, the event subscriptions are a bit janky, we're using the go-ethereum abigen bindings which allow for watching for events, but it seems they don't always fire at the right time. investigate this, maybe it's something we're doing, or it might be a limitation with go-ethereum as their docs seem to indicate this isn't fully implemented.

the current workaround is to poll for events, and to send network messages when some contract function has been called.

[noot]

could try this lib: https://github.com/HydroProtocol/ethereum-watcher