jp (file): file sharing + improvments: - file sending now handle --path and --namespace (used to specify how to share a file) - implemented file request, a file must be identified by it's name or hash, using --path when possible - added share subcommands - share/list allows to list file shared by an entity at a specific path - share/path allows one to share a local path privatly (only accessible by its bare jid), publicly or to a whitelist of jids