Disable ajax caching in IE to fix backbone fetching

This fixes all the IE issues that I experienced on the course outline page. @cahrens @benmcmorran 
I think we want to restrict the disabling of caching as much as possible. Just starting to read through some posts. http://stackoverflow.com/questions/367786/prevent-caching-of-ajax-call

http://stackoverflow.com/questions/6178366/backbone-js-fetch-results-cached