try to update broadcast

When I was working on cosmos sdk upgrade, I did some digging into how we broadcast tx to thorchain, and I found out , when cosmos finished processing the tx , it will return the result , and the response will always be mapped to a type call sdk.TxResponse refer to the following two places

https://github.com/cosmos/cosmos-sdk/blob/master/x/auth/client/rest/broadcast.go#L46 https://github.com/cosmos/cosmos-sdk/blob/master/client/context/broadcast.go#L19

Given that we don't need to parse the response two times