Fix for #1919 (branch Wescott master exercise work)

@jbau: Another small code review. I added a success function for the AJAX call to save answers, and I augmented the failure function a bit to clean up messaging slightly and store the answers in localStorage (yes, my fave backup these days) just in case. I also added an else clause to the getDialog function to change the title bar text if the dialog already exists. Tested the error case by stopping the server and issuing the Save Answers call.