Update freno help message handling

Currently the default behavior for running 'freno -help' is to emit a panic.  This overrides the default behavior of the flag package and makes it so there's no way to see the list of program options.  There is a program-specific usage message which is emitted when there are no arguments.  There's no reason to have separate behavior for this usage message and -help output, so this PR combines emiting program options with the custom usage message and gives this behavior to the 'no options' default program behavior and the '-help' argument.  This ensures that default expected behavior matched the actual program behavior

Author: gtowey

.gitignore

@@ -3,3 +3,4 @@ bin/
 main
 conf/freno.local.conf.json
 .vendor/
+freno

go/cmd/freno/main.go

@@ -43,7 +43,7 @@ func main() {
 	group.ForceLeadership = *forceLeadership
 
 	if *help {
-		printHelp()
+		printUsage()
 		return
 	}
 
@@ -83,8 +83,6 @@ func main() {
 	case *http:
 		err := httpServe()
 		log.Errore(err)
-	case *help:
-		printHelp()
 	default:
 		printUsage()
 	}
@@ -126,25 +124,22 @@ func httpServe() error {
 	return gohttp.ListenAndServe(fmt.Sprintf(":%d", port), router)
 }
 
-func printHelp() {
-	panic("not yet implemented")
-}
-
 func printUsage() {
 	fmt.Println(`Usage: freno [OPTIONS]
-	To run the freno service, execute:
-		freno --http
+  To run the freno service, execute:
+    freno --http
 
-	For more help options use: freno -help.
-
-	freno is a free and open source software.
-	  Please see https://github.com/github/freno/blob/master/README.md#license for license.
-	  Sources and binaries are found on https://github.com/github/freno/releases.
-	  Sources are also available by cloning https://github.com/github/freno.
+  freno is a free and open source software.
+    Please see https://github.com/github/freno/blob/master/README.md#license for license.
+    Sources and binaries are found on https://github.com/github/freno/releases.
+    Sources are also available by cloning https://github.com/github/freno.
 
   Issues can be sumbitted on https://github.com/github/freno/issues
-	Please see https://github.com/github/freno/blob/master/README.md#contributing for contributions
+  Please see https://github.com/github/freno/blob/master/README.md#contributing for contributions
+
+  Authored by GitHub engineering
+
+  OPTIONS:`)
 
-	Authored by GitHub engineering
-	`)
+	flag.PrintDefaults()
 }