Uses jquery-rails 3.0.4
Do not force User#send_credentials checkbox to be checked.
Create language tree dialog styling.
Adds fix for JSON error in asset pipeline.

- http://stackoverflow.com/questions/18394817/json-error-with-coffeescript-rails-asset-pipeline
- https://github.com/sstephenson/execjs/issues/129
Set User#send_credentials checkbox to checked in Admin::Users#new
Fixes a bug in 500 error view, where sometimes the alchemy routing proxy could not be found.