Hook for json.parse(...) to parse Xero date formats.

def json_load_object_hook(dct):
    """ Hook for json.parse(...) to parse Xero date formats.
    """
    for key, value in dct.items():
        if isinstance(value, six.string_types):
            value = parse_date(value)
            if value:
                dct[key] = value

    return dct