Include more information in return from sending transaction

[david-yan]

I would like to run gas benchmarks against a cluster but I can't easily do that with oasis-client since the address of the service/output of the call is returned directly from the receipt. It would be useful to include additional fields in the return statement, such as gas used. If we want to keep this simple, we can add an optional field that will return the transaction hash, and the client can request the receipt themself.

[armaniferrante]

This type of transaction information is purposefully left out of the top level client apis, which is being informed by design decisions in https://github.com/oasislabs/developer-gateway.

However, we can definitely consider adding more functionality here if there's demand.

For now, it's recommended to make raw web3 calls via the Web3Gateway to achieve this functionality.