Update Ember to 1.3 and latest Ember-data

[sindresorhus]

Followup to #670

Some things that needs to be fixed:

• The textbox for entering new todos isn't focused on load
• The text shouldn't be selected when entering editingmode

Notes from author:

• Uses debounce to ensure we only send one removeTodo action for consecutive focus-out and insert-newline events (fixes an error that ember-data otherwise would raise)
• Use bufferedTitle property in TodoController so that we can rollback changes to the todo on pressing 'escape'. (Required by spec)
• Does not use rollback() because it is not supported in ember-data beta 1 (and local storage adapter is not compatible with ember-data beta 2)

// @bantic

[sindresorhus]

@bantic @mixonic @trek do you know anyone that could be interested in getting the ember app up to date?

[bantic]

I will take a crack at this tomorrow.