Add UTCNow() function. (#3931)

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

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

cmd/lock-instrument.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.
@@ -157,7 +157,7 @@ func newDebugLockInfo(lockSource string, status statusType, readLock bool) debug
 		lockSource: lockSource,
 		lType:      lType,
 		status:     status,
-		since:      time.Now().UTC(),
+		since:      UTCNow(),
 	}
 }