nathanvda/cocoon — pull request #120 by virusman (2013-01-22 20:39:20+00:00)
Title: Make sure javascript_expansions config option exists

javascript_expansions config option has been removed in Rails 4 (along with all old asset concat tags), so we have to check for its existence first, like jquery-rails does:
https://github.com/rails/jquery-rails/blob/master/lib/jquery/rails/railtie.rb