command: Remove the useless "debug" subcommand

This is just a husk of a container command that has no nested commands
under it, so it isn't serving any purpose.

Author: apparentlymart

command/debug_command.go

@@ -95,7 +95,6 @@ func initCommands(
 
 	PlumbingCommands = map[string]struct{}{
 		"state":        struct{}{}, // includes all subcommands
-		"debug":        struct{}{}, // includes all subcommands
 		"force-unlock": struct{}{},
 		"push":         struct{}{},
 		"0.12upgrade":  struct{}{},
@@ -339,12 +338,6 @@ func initCommands(
 			}, nil
 		},
 
-		"debug": func() (cli.Command, error) {
-			return &command.DebugCommand{
-				Meta: meta,
-			}, nil
-		},
-
 		"force-unlock": func() (cli.Command, error) {
 			return &command.UnlockCommand{
 				Meta: meta,