* migrate torrentapproval to list storage
* add initial support for torrent file storage (watch directory with fsnotify)
* replace frontend/http/bencode package with github.com/zeebo/bencode module
* sanitize code (fix warnings)
TODO:
* parse torrent files to get hashes,
* watch directory event types
DON'T use for now
this makes it possible to specify a torrent whitelist/blacklist in the
configuration file based on their hexadecimal hash.
Fixes#375
Signed-off-by: Pierre-Alain TORET <pierre-alain.toret@protonmail.com>