CMS for Ruby or JavaScript

So I'm currently looking for a light weight CMS that allows for these features:

• WYSIWIG or Markdown editor

• Allows for editing of page content. Admins can then approve or deny said edits before posted

• Uploading files/images/etc to pages

The project is built out in Ruby on Rails. I'm comfortable also using a client side solution in JavaScript as well, since it uses Ember. Looked around but couldn't find many solutions. In people's experience, what kind of frameworks have people used for these kind of features?