Debug Assets broken

When I attempt to load a project with `set :debug_assets, true`, any javascripts which are required (and have been broken down for development) are not found. E.g. with `\\=require 'bootstrap'` from the "bootstrap-sass" gem, attempting to load `/javascripts/bootstrap.js` returns:

    File Not Found
    /javascripts/bootstrap.js
    If this is an an asset from a gem, add sprockets.import_asset 'bootstrap.js' to your config.rb.

I think the cause may be #23.