Allow service_id per service_type for Usage Events

    notification_service_id is not of type DictOpt,
    this allows for a comma-sep list of
    service_type:service_id pairs

Fixes: Bug 1215649
Change-Id: Ic747bf50bf6f4c2b705ecae96a7ead52ebcdae38
Merge "Allow service_id per service_type for Usage Events"