title: Is ACAccount thread safe?
body: <p>Can I share a single <code>ACAccount</code> instance between threads? Specifically I would like to create  multiple <code>TWRequest</code> objects that are used by different <code>NSOperationQueue</code> instances. Those <code>TWRequest</code> objects will share a single <code>ACAccount</code> instance. Is that safe?</p>
  
  <p>Thanks.</p>