Fixes bug 15177 - failure to disable forwarding.

Removes Listener attribute when it is no longer 
needed on the downstream port. Prevents an invalid
match that would cause a Lv not to be propagated back
to the node up the chain.
Fix for bug 15174. Invalid talker stream switch off.

The propagated flag was being cleared but then being
reset by MAP after the join. Now uses the here flag 
to prevent a Lv being propagated back.