Gulp watch does not rebuild Sass when imported file changes

Whenever a file changes, it calls the "style" pipeline.

```
$.watch(paths.styles)
    .pipe($.plumber())
    .pipe(styles())
    .pipe($.connect.reload());
```

However, if this is a imported file, the path passed to the line will be the file path, and not the main scss file which imports it, requiring me to save the main file to reload the css.
