Added ember built from master.

I wanted this:
https://github.com/emberjs/ember.js/pull/1838
Updated application code to be compatible with new Ember.

Store is easier to access + controller needs through get().
First go at regrets, see comment in regrets controller.
User are now able to regret a delete action.

Don't think this is 100% flawless, as we can run
in to problem in the timespan when the record
is in a deleted state, ember for some reason reloads
all records from server and tries to load data.

I have not encountered it in the current UI as the
code is now, but I did encounter it when I
transitioned to 'index' instead of 'lists'. Ember
then reloaded all lists, and BOOM we where kinda
fucked.
Implemented close-button on regrets. Will delete when closed.
Simplified how we render regrets, don't set it up in the app route.
Updated README.
Merge branch 'regrets'