message: change spawn middleware to properly create bot.api
diff: @@ -164,18 +164,13 @@ function GoogleHangoutsBot(configuration) {
  .getClient(params)
  .then(client => {
  worker.authClient = client;
  + worker.api = google.chat({version: api_version, auth: worker.authClient});;
  + next();
  })
  .catch(err => {
  console.error('Could not get google auth client !');
  throw new Error(err);
  });
  -
  - const chat = google.chat({version: api_version, auth: bot.authClient});
  -
  - bot.api = chat;
  -
  - next();
  -
  });
  google_hangouts_botkit.middleware.normalize.use(function handlePostback(bot, message, next) {
  