Release Note

1. Update the -q option, indicating the overall qps to be limited, instead of each worker by -c, introducing uber-go/ratelimit to achieve the rate limit function.
2. Optimise the CTRL-C interruption, canceling the on-ongoing requests, and do not statistic canceled requests.
3. Add the -l option to log all the responses for debugging during a performance test.
4. Add the -bc option to check the error code internal HTTP body as JSON string. This is for some applications does not follow RESTFul API style, returning the error code inside the HTTP body and returning http status code 200 always. the error code filed is extracted with tidwall/gjson