Add edit icon to action toolbar

The action toolbar should include an 'edit' icon.

Clicking on the edit button enables the user to change the original values they inputted when creating the item.

![screen shot 2014-09-18 at 1 44 31 pm](https://cloud.githubusercontent.com/assets/1521387/4319236/b6042fd6-3f29-11e4-9835-b19d52ea5b4d.png)



I understand your reasoning. I've tried out both approaches in the past on backbone things, and found the simpler approach was to serialize a backup copy which we just reassign if they click *Cancel*.

I guess this is the kind of case where those immutable data structure languages like clojurescript win :)