backporting fix to rails/rails#8119 from
https://github.com/rails/rails/commit/445f14e97553de552745de26ebd5e49bc5c82f4e
(e.g. to deal with jasmine-rails spec/assets paths)
[fixes #119] Remove Configurable usage

Configurable was not behaving correctly when used on the sprockets helper module. This PR removes this dependency and we will use a class accessor directly instead.
Merge pull request #120 from schneems/schneems/fix-configurable

[fixes #119] Remove Configurable usage
Merge pull request #121 from red56/master

backporting fix to rails/rails#8119 from