BREAKING
Example response:
```json
{
"jsonrpc": "2.0",
"id": "",
"result": {
"height": "2109",
"txs_results": null,
"validator_updates": null,
"consensus_param_updates": null
}
}
```
Old result consisted of ABCIResponses struct and height. Exposing
internal ABCI structures (which we store in state package) in RPC seems
bad to me for the following reasons:
1) high risk of breaking the API when somebody changes internal structs
(HAPPENED HERE!)
2) RPC is aware of ABCI, which I'm not sure we want
