Moved lint success/pass to messages constant, simplified the success message.

Could have done this in the last patch, however I think it's best to not modify too many things at once making PRs easier to deal with. Anyway, I changed this because I thought it was a little verbose:

```
>> All spaces are correct.
>> 5 files checked.

becomes:

>> 5 files lint free.
```

Also, moved the pass/fail messages to the array so they are easier to test.