PreviewView now extends (React)EditorView

@ddavison could you please test this out. Thanks! :)

Closes #32.

Fixes:
- #31 
- #25
- #27
- #43
- #44

Screenshot(s):
![show error message](https://cloud.githubusercontent.com/assets/1885333/3868544/8971a9e0-204c-11e4-817c-cd38ba462735.png)