Removed 

Removed config.action_view.javascript_expansions code, because it seems unnecessary and causes an error in Rails 4. 

Adding to the "config.action_view.javascript_expansions" hash is only necessary if javascript_include_tag(:cocoon) needs to require multiple files, which doesn't appear to be the case.

I also changed gem 'sqlite-ruby' to gem 'sqlite' in order to prevent a warning that I saw when running bundle install for cocoon.