main/cli: Don't print hidden flags/commands in help template. (#3748)

Always use .VisibleFlags and .VisibleCommands to not print
Hidden flags as expected from help template.

cmd/main.go

@@ -53,13 +53,13 @@ DESCRIPTION:
   {{.Description}}
 
 USAGE:
-  minio {{if .Flags}}[flags] {{end}}command{{if .Flags}}{{end}} [arguments...]
+  minio {{if .VisibleFlags}}[flags] {{end}}command{{if .VisibleFlags}}{{end}} [arguments...]
 
 COMMANDS:
-  {{range .Commands}}{{join .Names ", "}}{{ "\t" }}{{.Usage}}
-  {{end}}{{if .Flags}}
+  {{range .VisibleCommands}}{{join .Names ", "}}{{ "\t" }}{{.Usage}}
+  {{end}}{{if .VisibleFlags}}
 FLAGS:
-  {{range .Flags}}{{.}}
+  {{range .VisibleFlags}}{{.}}
   {{end}}{{end}}
 VERSION:
   ` + Version +