Disable usage output on errors

This causes command help messages to appear everytime an error is triggered.

pkg/cmd/dcos.go

@@ -19,7 +19,8 @@ const annotationUsageOptions string = "usage_options"
 func NewDCOSCommand(ctx api.Context) *cobra.Command {
  var verbose int
  cmd := &cobra.Command{
- Use: "dcos",
+ Use: "dcos",
+ SilenceUsage: true,
  PersistentPreRun: func(cmd *cobra.Command, args []string) {
  if verbose == 1 {
  // -v sets the logger level to info.
@@ -91,7 +92,6 @@ func pluginCommand(executable string, pluginManager *plugin.Manager, c *plugin.C
  Short: c.Description,
  DisableFlagParsing: true,
  SilenceErrors: true, // Silences error message if command returns an exit code.
- SilenceUsage: true, // Silences usage information from the wrapper CLI on error.
  RunE: func(cmd *cobra.Command, args []string) error {
  // Prepend the arguments with the commands name so that the
  // executed command knows which subcommand to execute (e.g.