Improvement on the Adapter part of the README

[Dainii]

Hello !

Thank you for this addon.

Just a quick feedback, when implementing this on my application, I had some issue doing request with ember-data. It turns out that the handleResponse(status) function suggested never returns the payload to ember-data, generating error like "Error while processing route: authenticated.model You made a 'findAll' request for 'model' records, but the adapter's response did not have any data".

I changed it to

handleResponse(status, headers, payload, requestData) {
  if (status === 401 && this.session.isAuthenticated) {
    this.session.invalidate();
  }

  return super.handleResponse(status, headers, payload, requestData);
}

I'm no expert in Javascript, so maybe there is a better way to do this.