Use edge Ember-Rails and update application to new router 

The first commit updates your Gemfile to use the latest version of Ember-Rails, which by default means you will always be using the latest official release of Ember and Ember Data.

The second commit updates your application to be compatible with the latest Ember and Ember Data. A few points:

-Ember now automatically generates generic instances of controllers, views, and routes, so I was able to delete some files where non-default behaviour was not required. 

-I updated the store to use revision 11. Revision 12 is available in the master branch of Ember-Data, but that hasn't been released with a version number yet (and hence is not used by Ember-Rails by default). If you use `rails generate ember:install --head` then you will need to update this to 12.

-I created a `Seeds` route and set it's path to root. The `loadSeeds` method is now called by the route. It renders into the `Application` template through the `{{outlet}}`

-Things are instantiated differently with the new router, so some `create`s became `extend`s.

-I used a `{{render}}` tag instead of `{{view}}` for rendering a `Seed`. This is good because the `Seed` template doesn't need to prefix bindings with `view` and it makes use of the `SeedController` which is auto-generated right now, but could be overridden to add controller functionality to each rendered item.

-You might need to delete `tmp/cache` to clear templates compiled with older versions of Ember.

Good luck and give me a shout if you have any issues.