Add inspect methods to models

This adds #inspect and .inspect to the models. A few notes:

* The type detection isn't all I'd like it to be, but ROXML doesn't make it easy to figure out what something was declared as.
* I'd like to inspect child models, but there would need to be cycle detection.
* I'm open to the idea that this should go in ROXML, but it also seems OK here.
* I'm in to the idea of adding inspect methods for services and collections too, but haven't quite figured out what it should look like(except for Service.inspect, which should probably just delegate to the model.)