synchronisation used to be skipped when the node was existing and `resync` was not set,
however the case happens when a node is subscribed but not synchronised, thus this patch
update the behaviour to be sure to have the node synchronised.
rel 369
- cache only latest 20 items when disco infos are hidden and thus we can't discover
feature/RSM implementation
- better handling of args when calling `storage.getItems`
rel 365