I'm not sure this will really work.. Version number comparison is hard, and `cmp` just does simple string comparions, e.g:

```
>>> cmp('3.0.10', "30.0.2")
-1
>>> cmp('3.0.10', "30.0.11")
-1
```

What about just having a separate file like `tvnamer3.json`? Easier for migrating, and don't have to worry about backwards compatibility