code: public RequestToken refresh(boolean withAcl,BaasHandler<BaasDocument> handler){
          return doRefresh(withAcl,RequestOptions.DEFAULT,handler);
      }
docs: Asynchronously refresh the content of this document.
  *
  @param withAcl if true will fetch acl
  @param handler a callback to be invoked with the result of the request
  @return a {@link com.baasbox.android.RequestToken} to handle the asynchronous request
  @throws java.lang.IllegalStateException if this document has no id