Refactor logger (#3924)

This patch fixes below

* Previously fatalIf() never writes log other than first logging target.
* quiet flag is not honored to show progress messages other than startup messages.
* Removes console package usage for progress messages.

cmd/logger_test.go

@@ -1,5 +1,5 @@
 /*
- * Minio Cloud Storage (C) 2015 Minio, Inc.
+ * Minio Cloud Storage (C) 2015, 2016, 2017 Minio, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,48 +17,15 @@
 package cmd
 
 import (
-	"bytes"
-	"encoding/json"
-	"errors"
 	"testing"
-
-	"github.com/Sirupsen/logrus"
 )
 
-// Tests callerSource.
-func TestCallerSource(t *testing.T) {
-	currentSource := func() string { return callerSource() }
+// Tests getSource().
+func TestGetSource(t *testing.T) {
+	currentSource := func() string { return getSource() }
 	gotSource := currentSource()
-	expectedSource := "[logger_test.go:31:TestCallerSource()]"
+	expectedSource := "[logger_test.go:26:TestGetSource()]"
 	if gotSource != expectedSource {
 		t.Errorf("expected : %s, got : %s", expectedSource, gotSource)
 	}
 }
-
-// Tests error logger.
-func TestLogger(t *testing.T) {
-	var buffer bytes.Buffer
-	var fields logrus.Fields
-	testLog := logrus.New()
-	testLog.Out = &buffer
-	testLog.Formatter = new(logrus.JSONFormatter)
-	log.mu.Lock()
-	log.loggers = append(log.loggers, testLog)
-	log.mu.Unlock()
-
-	errorIf(errors.New("Fake error"), "Failed with error.")
-	err := json.Unmarshal(buffer.Bytes(), &fields)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if fields["level"] != "error" {
-		t.Fatalf("Expected error, got %s", fields["level"])
-	}
-	msg, ok := fields["cause"]
-	if !ok {
-		t.Fatal("Cause field missing")
-	}
-	if msg != "Fake error" {
-		t.Fatal("Cause field has unexpected message", msg)
-	}
-}