How can I upgrade ember-rails' version of ember-data to revision 12? - ember-data

Question

I've got ember-rails updated to master:
bundle update ember-rails
Updating git://github.com/emberjs/ember-rails.git
Fetching gem metadata from https://rubygems.org/.........
....
Using ember-rails (0.11.1) from git://github.com/emberjs/ember-rails.git (at master)
....
Your bundle is updated!
I'd like to use the latest ember-data revision (12), but every time I update my app's store revision number to 12, i.e.:
App.Store = DS.Store.extend({
revision: 12,
adapter: App.Adapter.create()
});
I see the following error message:
Uncaught Error: Error: The Ember Data library has had breaking API changes since the last time you updated the library. Please review the list of breaking changes at https://github.com/emberjs/data/blob/master/BREAKING_CHANGES.md, then update your store's `revision` property to 11
...and when I check out DS.CURRENT_API_REVISION it's 11:
console.log(DS.CURRENT_API_REVISION); // 11
Is there a way to get the gem to pull in revision 12, or do I have to build ember-data myself and override the included version?

Answer 1

benburton's solution works for what is asked for, but in the latest ember-data it uses an internal method 'readOnly' that was only added to in ember RC2.
Therefore, you need the latest ember in order to run the latest ember-data. The full solution is to simply disregard the second line of your solution, leaving the following:
rails generate ember:install --head

Answer 2

I ended up using ember-rails to generate ember+ember-data and then removing the updated version of Ember like so:
rails generate ember:install --head
rm vendor/assets/ember/development/ember.js vendor/assets/ember/production/ember.js