Dh/feature editor preview

Hey guys I added preview functionality to the editor, as well as some general "best practices" to editor.js

![anchor-editor-update-editing](https://cloud.githubusercontent.com/assets/1771664/4691303/9e8a2978-5711-11e4-8456-c033a1ea2dc4.png)

![anchor-editor-update-previewing](https://cloud.githubusercontent.com/assets/1771664/4691305/a183f0be-5711-11e4-801c-c7a3aa8a1731.png)