Check for missing event handler

[CumpsD]

Our logging sometimes shows a warning of this kind:

Could not resolve a handler for AddressPositionWasRemoved.

This is caused by events coming in, which are missing an event handler. This is most likely to happen in the syndication handlers.

This warning is noise since it requires no action. We have simply decided for event X we are not interested in it, which is a valid use case.

This has to be made more explicit by actually handling that event and doing nothing with it, instead of generating a warning.

Please review this registry for occurrences like this and fix them.