On-chain ACL checker for secretstore

[svyatonik]

on top of #4974
@keorn as agreed yesterday - here's the chain-based AclChecker prototype. Are you going to develop the contract itself? I'll need a contract ABI to generate something like this:
https://github.com/paritytech/parity/blob/master/ethcore/src/miner/service_transaction_checker.rs#L58
Also - are we going to deploy registry contract && get ACL checker contract address from there, or would it be hardcoded/cli-option address?

[gavofyork]

would prefer to have the registry throughout.

[svyatonik]

Checked success && failure cases on Kovan

[rphmeier]

LGTM; I wonder if we could put the contract into the native_contracts crate at some point?

[svyatonik]

I thought about it, but as I understand it is for 'core' functionality, while this one is secretstore-specific && secretstore itself is very specific. So do not know if this is a good idea.
Maybe it would be better to use macros from native_contracts to generate this file?

[gavofyork]

i think it's fine to have in there. it's not a huge maintenance burden and it's super convenient.

[svyatonik]

ok, will move there

[svyatonik]

done

[rphmeier]

it is for 'core' functionality

I meant it to be a bin for all contracts we use from Parity (which I suppose includes this)

[svyatonik]

Ok, got it :) I thought that, because it doesn't include updater contract. But I suppose it is in TODO list.