new mbean register/unregister notification for groups of mbeans

in order to scale things like cascades of mbeans and virtual mbeans (more generally,
anything using an interceptor to fake the existence of groups of mbeans) it would
be valuable to have the next JMX spec detail that a different notification may be sent
than that of

MBeanServerNotification.REGISTRATION_NOTIFICATION | UNREGISTRATION_NOTIFICATION

in particular, a notification of the same form but containing an ObjectName pattern instead of an ObjectName would appear to be the most appropriate. This could be spec'd as the instance info for any mbean with this pattern can be considered to need refreshing (via a query with the same pattern).