Extract BaseView class methods to ViewAdapter.
Filter viewAdapter attach to only handle "top level" data-views, deferring attachment of nested to their own views/
Defer attachment strategy to view's class.

Allow optional callback for BaseView getHtml. Use callback for server getViewHtml to allow different viewAdapters to be async.

Remove backbone view dependency on AppView. Add renderInside to view instances for view-tech agnostic rendering.