fixed #1464 - change so persistence dir is only backed up if node is HA ...

...master or HA disabled; handles the case of HA autodetect selecting master hence the complexity.

also fixes some leaks in test and improves atomic file update support in FileBasedObjectStore.
(incorporates new logging from #1469)
Overall I agree with your default here - but this feels overly complicated. I just don't know which options we'd remove to simplify it! So happy to leave as-is.