do not require sprockets its unnecessary
do not require sprockets its unnecessary

- avoid the manifest file error running on Rails 5.1

```
Sprockets::Railtie::ManifestNeededError:
  Expected to find a manifest file in `app/assets/config/manifest.js`
  But did not, please create this file and use it to link any assets that need
  to be rendered by your app:

  Example:
    //= link_tree ../images
    //= link_directory ../javascripts .js
    //= link_directory ../stylesheets .css
  and restart your server
```

ma2gedev/breadcrumble,ma2gedev/breadcrumble