(For Jay) Add live preview to create/edit modal

@jaypatel24 

![image](https://cloud.githubusercontent.com/assets/2940142/3916841/92ee790c-2381-11e4-8a86-7bf613fa61c2.png)


Not positive about styling, but I think it looks alright
E is 'element' which means it needs to be a node in the DOM, like `<markdown></markdown>` while A is 'attribute' so it needs to be an attr on an element like `<div markdown></div>`, 'AE' just allows both.