Overrides doesn't match relative paths

JSHint doesn't override configuration when it is called with a
relative path, like `./src/bar.js` when the configuration is:

```json
{
  overrides: {
    "src/bar.js"
  }
}
```
Merge pull request #1765 from ysbaddaden/bug-overrides-option-and-relative-paths

Overrides doesn't match relative paths