View Hierarchy Debugging Improvements

Encouraged by #65 this morning, I spent some time improving the view hierarchy debugging functionality. This PR adds support for displaying object typed attributes on view nodes in the hierarchy. NSString attributes can be live edited. 

![String viewing/editing](https://f.cloud.github.com/assets/1422245/468798/1d01ee06-b6a2-11e2-9d6e-b735dd51e83c.png)

The view "class" fields now also display the view controller's class where appropriate.

![view controller class](https://f.cloud.github.com/assets/1422245/468785/c6438f66-b6a1-11e2-8270-561e7edd9f6a.png) 

Finally, some minor fixes to support readonly properties and quiet KVC exceptions were added.