Convert wrapper scripts to library calls

So far, I've converted the cabal check and hlint checks to use their respective libraries instead of calling external commands. They appear to work against git-vogue itself, but here's the output that gets generated below on success:

```text
cabal succeeded with No errors or warnings could be found in the package.

hlint succeeded with 
Stylish Haskell succeeded with Check passed
```

Doesn't seem like the nicest output. Was wanting people's thoughts on how we should clean it up, especially the hlint success message.