public string Authorize(string redirectTo)
{
 return string.Format(AuthorizeUri, Config.AppId, redirectTo);
}
public ActionResult GetFbCode()
{
 var fbSocial = currentUser.Socials.Where(p => p.Provider == "facebook").FirstOrDefault();
 if (fbSocial != null)
 {
 return RedirectToAction("Index");
 }
 else
 {
 return Redirect(fbProvider.Authorize("http://" + HostName + "/Social/SaveFbCode"));
 }
}