fix rebase, use 'object::user:<username>' or 'object::store:<storageid> as storage id, by default use container/bucket name for storageid, make storageid configurable, store user only for HomeObjectStoreStorage, change updateObject() to writeObject()

add autocreate config option for containers, implement autocreate and delete of containers, use generated container names for tests

fix checking unset array values, deduplicate code, remove file from cache if it could not be stored in the objectstore