/// <summary>
/// Makes an asynchronous http POST request to the specified url.
/// </summary>
/// <param name="url">The url to send the request to.</param>
/// <param name="prepareRequest">A callback that initializes the request with default values.</param>
/// <param name="postData">form url encoded data.</param>
/// <returns>A <see cref="Task{IResponse}"/>.</returns>
public Task <IResponse> Post(string url, Action <IRequest> prepareRequest, IDictionary <string, string> postData)
{
Log.WriteLine("POST url: " + url);
Log.WriteLine("POST-data: " + PostData2String(postData));
Task <IResponse> t = dhc.Post(url, prepareRequest, postData);
t.ContinueWith(tr => { Log.WriteLine("Response: " + tr.Result.ReadAsString()); }, TaskContinuationOptions.OnlyOnRanToCompletion);
return(t);
}