Save renaming history in database file: - [ ] Use [bolt](https://github.com/boltdb/bolt) for database - [ ] Command `history` to look at the history of a file - [ ] Command `undo` to undo renaming action - [ ] Use video file hash as keys ([OSDb hash](http://trac.opensubtitles.org/projects/opensubtitles/wiki/HashSourceCodes))