message: Add option to disable default startup message
diff: @@ -1223,7 +1223,9 @@ function Botkit(configuration) {
  });
  botkit.debug = botkit.log.debug;
  + if (!botkit.config.disable_startup_message) {
  console.log('Initializing Botkit v' + botkit.version());
  + }
  if (configuration.storage) {
  if (
  