message: Fix slackbot worker tests to exit
  jscs formatting changes
diff: @@ -54,6 +54,7 @@ describe('startRTM', () => {
  expect(cb).toHaveBeenCalledTimes(1);
  bot.closeRTM();
  + bot.destroy();
  const errorArg = cb.mock.calls[0][0];
  expect(errorArg).toBeNull();
  @@ -75,6 +76,7 @@ describe('startRTM', () => {
  expect(mockRequest.post).toHaveBeenCalledTimes(1);
  expect(cb).toHaveBeenCalledTimes(1);
  bot.closeRTM();
  + bot.destroy();
  const errorArg = cb.mock.calls[0][0];
  expect(errorArg).toBe('test_error');
  @@ -101,6 +103,7 @@ describe('startRTM', () => {
  expect(cb).toHaveBeenCalledTimes(1);
  bot.closeRTM();
  + bot.destroy();
  const errorArg = cb.mock.calls[0][0];
  expect(errorArg).toBe('test websocket error');
  