public UnSubscribeFromGCM(GCMSubscriptionId id, string userId, string token)
 {
     Id = id;
     UserId = userId;
     Token = token;
 }
 public UserSubscribedForGCM(GCMSubscriptionId id, string userId, string token)
 {
     Id = id;
     UserId = userId;
     Token = token;
 }