Remove compatibility for old Sprockets
Remove compatibility for old Sprockets

This is a workaround to avoid logical path normalization.
This is unnecessary since Sprockets 3.1.0.

> Removed "index" logical path normalization. Asset#logical_path is always the full logical path to the index file.

ref: https://github.com/rails/sprockets/blob/v3.1.0/CHANGELOG.md

tricknotes/ember-handlebars-template,tricknotes/ember-handlebars-template