add log format

[180909]

What is the purpose of the change

Easy log output

Brief changelog

Add rlog.Debugf() rlog.Infof() rlog.Warningf() rlog.Errorf() rlog.Fatalf()

[wenfengwang]

Could you tell us why we need the improvement?

[180909]

I read the source, and find this:

rocketmq-client-go/consumer/statistics.go

Lines 449 to 455 in 4065610

	rlog.Info("Stats In One Day, SUM: %d TPS: AVGPT: %.2f", map[string]interface{}{
	"statsName": si.statsName,
	"statsKey": si.statsKey,
	"SUM": ss.sum,
	"TPS": fmt.Sprintf("%.2f", ss.tps),
	"AVGPT": ss.avgpt,
	})