This commit ensures that all tickers are stopped using defer ticker.Stop()
style. This will also fix one bug seen when a client starts to listen to
event notifications and that case will result a leak in tickers.
This is an effort to remove panic from the source.
Add a new call called CriticialIf, that calls LogIf and exits.
Replace panics with one of CriticalIf, FatalIf and a return of error.
fixes a regression introduced in 0e4431725c
when removing a previously applied notification configuration.
event.ParseConfig() was stricter in terms of handling notification
configuration, we need to allow when notification configuration is
sent empty, this is the way to remove notification configuration.
Anis Elleuch