message: Add delete greating message
diff: @@ -426,7 +426,9 @@ function Facebookbot(configuration) {
  },
  delete_greeting: function() {
  var message = {
  - 'setting_type': 'greeting',
  + "fields":[
  + "greeting"
  + ]
  };
  facebook_botkit.api.messenger_profile.deleteAPI(message);
  },
  