implement bash / zsh functions

[ORESoftware]

https://github.com/dthree/vorpal/wiki/api-%7C-vorpal.command#commandallowunknownoptions

.command.allowUnknownOptions()

//Allow for unknown options to be passed into a command. Disable options validation.

vorpal
  .command('foo')
  .allowUnknownOptions()
  .action(function(args, cb){
    // ...action
  });