This is the proposed config:

```js
// Automatically inject Bower components into the HTML file
bowerInstall: {
  app: {
    src: ['<%= yeoman.app %>/index.html'],
    exclude: ['bower_components/bootstrap-sass/vendor/assets/javascripts/bootstrap.js']
  },

  sass: {
    src: ['<%= yeoman.app %>/styles/{,*/}*.{scss,sass}'],
    ignorePath: 'bower_components/'
  }
}
```

`ignorePath` option removes the specified string from the include path. Previously `bower_components` was in the `app` folder, which would by itself make grunt-bower-install output paths like these:

```html
<!-- app/index.html -->
<script src="app/bower_components/jquery/jquery.js"></script>
```

But in this case `app/index.html` would be searching for that file in `app/app/bower_components`. To get rid of the `app/` part, you specify it like this: `ignorePath: 'app/'`