Add UTCNow() function. (#3931)

This patch adds UTCNow() function which returns current UTC time.

This is equivalent of UTCNow() == time.Now().UTC()

cmd/lockinfo-handlers.go

@@ -1,5 +1,5 @@
 /*
- * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ * Minio Cloud Storage, (C) 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.
@@ -71,7 +71,7 @@ func listLocksInfo(bucket, prefix string, duration time.Duration) []VolumeLockIn
 	defer globalNSMutex.lockMapMutex.Unlock()
 
 	// Fetch current time once instead of fetching system time for every lock.
-	timeNow := time.Now().UTC()
+	timeNow := UTCNow()
 	volumeLocks := []VolumeLockInfo{}
 
 	for param, debugLock := range globalNSMutex.debugLockMap {