Merge pull request #160 in ZP/z-push from feature/ZP-622-ping-should-notify-on-hierarchy-changes to develop

* commit 'f3c891be':
  ZP-778 Remove unused code.
  ZP-622 Devices performing heartbeat weren't handling changes properly.
  ZP-622 Update year.
  ZP-778 Make sure the hierarchy cache is loaded when verifying hierarchy changes in SyncCollections.
  ZP-777 Verify potential hierarchy changes against a hierarchy hash coming from all foldernames + parent ids.
  ZP-622 Update year.
  ZP-771 Indicate changed additional folderdata in DeviceManager->IsHierarchySyncRequired().
  ZP-778 Verify received hierarchy notifications for validity.
  ZP-777 Catch and filter hierarchy events.
  ZP-622 added HIERARCHYNOTIFICATION constant to the IBackend.