- Add a new block to the RKPaginator contract that is guaranteed to be f...

...ired only *after* the underlying page load operation has finished. This makes sense because there is a conceptual difference between the success/failure blocks which are passed *into* the underlying operation(s) for a Paginator vs management of the Paginator itself. Any code that operates on the Paginator when a page is loaded (for example, to make a Paginator enumerate through all pages) should go in the new pageFinishedBlock.