public static void UpdateOrAddFamilyAttribute(int familyId, string key, string value, HttpRequest.RequestResult resultHandler)
{
string urlEncodedValue = System.Net.WebUtility.UrlEncode(value);
string oDataFilter = string.Format("/{0}?attributeKey={1}&attributeValue={2}", familyId, key, urlEncodedValue);
//todo: add delete
RockApi.Post_Groups_AttributeValue(oDataFilter, resultHandler);
}