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)



Two questions:
  - Why do we hide connected endpoints?
  - Would we want to add this kind of handling to conversations and channels?