HTML5 Offline Cache Manifest file with asset pipeline in Rails 3.2 app?

Rails
1

*This question is also available in Stack Overflow:
linkhttp://stackoverflow.com/questions/10948748/html5-offline-cache-manifest-file-with-asset-pipeline-in-rails-3-2-app
*

I’m a newbie in programming.
The app I’d created is http://checkamy.herokuapp.com (Welcome any
comments)

It’s very simiple: a few .coffee, .scss and images.
In what way I should do to make my app offline?

I read some HTML5 books and understand how-to. But I don’t know how
to implement in Rails 3.1+.
“Rack-offline” seems outdated and I read this:

CACHE MANIFEST

javascripts/application.js
javascripts/jquery.js
images/masthead.png

NETWORK:
/

They are not application-xxxxxxxx.js

I guess the browser will download 2 different files: 1 online
app-xxxx.js
and 1 offline app.js. (waste server resources)

And the application.js is possible to be outdated, right?

So, what should I do to achieve the offline browsing feature?

Please help. Thanks in advance.