public string InvokeAPI(string action, Dictionary<string, string> parameters)
{
var url = string.Format(API + "&{1}", action,
string.Join("&",
parameters.Select(kvp =>
string.Format("{0}={1}", HttpUtility.UrlEncode(kvp.Key), HttpUtility.UrlEncode(kvp.Value)))));
return WebClientEx.DownloadContent(url, 1, 1500);
}