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)
I like dumping grounds!  It makes things easier to find.  `BrooklynShutdownHooks` is only obvious in hindsight...