Manually added nodes are ignored on re-render

[metaist]

Example: http://jsfiddle.net/v6Pn5/

I use this pattern to add items to a list before a model fully exists (e.g., clicking "add item" in a todo list) and then I re-render the list once the item is persisted on the backend.

The issue might be related to #11, specifically with the instanceCache not being updated (or busted).

Any chance we can add a cache-busting option to .render?