More ContractInfo

[alpe]

Builds on #251 and #241

Besides API, do we want to store more info?

• If two contracts are linked together, deployed as a bundle, maybe this is stored?
• Linking contract to token vouchers? (if implemented)
• Some sort of permission levels if we can control minting, etc from contract?

And how to set such metadata?

[ethanfrey]

I think this was mostly addressed by letting chains extend ContractInfo.
We don't need to handle these use cases in wasmd, but allow chains to import x/wasm and add such functionality without forking.

Maybe just document how one could do such a process? I see no code changes needed in the core library

[ethanfrey]

@alpe can we close this? Anything else to add?

I see #584 as relevant, but I think this was solved by the extensions support you have added.