Don't create drafts every time a component is edited.

TNL-399
I'd rather not have the django app have to dig into the XBlock internals, simply because it makes it harder for us to make changes in the future (we've talked before about changing the dirty fields implementation).

The xblock persists changes in both studio and student views. In studio view, it has r/w access to scope.content and scope.settings, but in student view, it only has read access to those, while having r/w access to user state.

I suppose you could restrict studio_view to only have read access to fields, and not write access, but that seems less consistent w/ how we render other views.