Fix of bug in Notificator class

Deleting of listner from listenersByStreamName map was corrected
try, finally block was added for locking, unlocking of access to map

Change-Id: I60ecb9c247af18436f348d4f4827c7f75fdfaeaa
Signed-off-by: Jozef Gloncak <jgloncak@cisco.com>
Merge "Fix of bug in Notificator class"