Store view references

[danielstorey]

Store references to views on the page so that view instances can be retrieved at will without having to first store them by listening to all the different 'someView:postRender' events.

View references should be stored as child views on the parent. This will ensure that references remain in context of the Adapt model hierarchy, and that all references are removed when the location changes, so as to prevent memory leaks.

A findDescendantViews method should be created, to work in the same way as findDescendantModels

A getViewByModelId method would also be quite handy