[Issue #14] Remove jquery-mockjax requirement

It is less obtrusive, but it is also more dangerous. Consider the case where a user has a client-side script that happens to be requesting data from the same url as one of the model/collection fetch calls. Now you've introduced a race condition because mockjax will mock out the response for any ajax call to that url, where as this solution is more tightly integrated with the syncing workflow. Also this solution would obviously be more performant because there is less work to do.

If it's just a matter of the result looking the same, I would rather solve that by faking the jqxhr rather than pushing this functionality all the way down to the $.ajax level.