Moved RetryPolicy check to FaultManager

This allows us to keep the notification error stream as typed exceptions.
Fixed issue with notifications acceptance test would sometimes miss events.
Reusing default SLR settings for both config section and FaultManager.
Added validation rules to SecondLevelRetriesConfig section.
Merge pull request #2509 from Particular/SLR_Refactor

Moved RetryPolicy check to FaultManager