Change Kill Bill lifecycle:
- Add new specific events for PLUGIN (INIT_PLUGIN/START_PLUGIN/STOP_PLUGIN)
- Remove REGISTER/UNREGISTER events and merge the logic in INITIALIZE/STOP
Fix flacky TestIntegrationWithAutoPayOff (the fix is a bit of hack dur to missing API for tracking when a bus event has been fully processed by all handlers)
Merge remote-tracking branch 'origin/master' into leaner-build