Fixing the case where a user enters a single '.' as a CLI argument

This is related to jgonera/autoless#4 and jgonera/autoless#5

We got this _almost_ fixed 6 months ago, but I ran into it again today without thinking because my solution didn't cover the use case of:

```bash
$ autoless .
```

It was difficult to fix this at the same place as in manager.js as I did in #4, and since I think this is probably a pretty CLI-unique case, I dropped into the bin exec file and swapped it there before it passes args to the manager object. 

It definitely fixes the problem I was having—thoughts?