Ember unable to copy image to correct path

I am developing a Ember project as addon and am trying to add loading image icon to my project.

My CSS class looks like

.loader {
    background: url("assets/images/loading.gif");
}

Now I am not sure where to place the image. I place the image in "public/assets/images" and it is not getting reflected on page.

In my dist directory, there are 3 folders

- assets/images
- addon-iuse/assets/images
- my-app/assets/images

I see the image only if I "manually" copy it under assets/images (1st path above)

But I do not know how I can get it there, since from the build process, it is copying under my-app/assets/images (3rd path above)

Just to add (not sure if this might be the reason), in my ember-cli-build.js, I have

var addoniuseassets = new Funnel('node_modules/addon-iuse/public', {
       srcDir: '/assets',
       destDir: '/assets'
  });