Update _refresh_data method to update object state variables on refresh
Update _refresh_data method to update object state variables on refresh

Add check-and-update steps to the JSONData._refresh_data() method to
ensure that the object state variables _json_attributes and
_access_control are updated when new JSON attributes are present in the
refreshing json_data.

Also, remove redundant call to json_data_to_dict() function from
JSONData._init_values() method:  _init_values() calls _refresh_data()
which also calls json_data_to_dict().

cmlccie/cmlCiscoSparkSDK