return a response_dict  with a list of search results in decending
    order based on a sort key

def query_mongo_sort_decend(
        database_name,
        collection_name,
        query={},
        skip=0,
        limit=getattr(
            settings,
            'MONGO_LIMIT',
            200),
    return_keys=(),
        sortkey=None):
    """return a response_dict  with a list of search results in decending
    order based on a sort key
    """

    l = []
    response_dict = {}

    try:
        mongodb_client_url = getattr(settings, 'MONGODB_CLIENT',
                                     'mongodb://localhost:27017/')
        mc = MongoClient(mongodb_client_url,document_class=OrderedDict)

        db = mc[str(database_name)]
        collection = db[str(collection_name)]

        if return_keys:
            return_dict = {}
            for k in return_keys:
                return_dict[k] = 1
            # print "returndict=",return_dict
            mysearchresult = collection.find(
                query, return_dict).skip(skip).limit(limit).sort(
                sortkey, DESCENDING)
        else:
            mysearchresult = collection.find(query).skip(
                skip).limit(limit).sort(sortkey, DESCENDING)

        # response_dict['num_results']=int(mysearchresult.count(with_limit_and_skip=False))
        response_dict['code'] = 200
        response_dict['type'] = "search-results"
        for d in mysearchresult:
            d['id'] = d['_id'].__str__()
            del d['_id']
            l.append(d)
        response_dict['results'] = l

    except:
        print("Error reading from Mongo")
        print(str(sys.exc_info()))
        response_dict['num_results'] = 0
        response_dict['code'] = 500
        response_dict['type'] = "Error"
        response_dict['results'] = []
        response_dict['message'] = str(sys.exc_info())
    return response_dict