When checking a possibly long-running requirement test, provide some feedback to the user

[bfitzpat]

Right now if you click "Validate All" on the Create a New Didact Tutorial Extension tutorial, it can take a while. But you click it and it just "goes away" -- like nothing happened. Then, a few seconds later, it updates.

We should provide some feedback to the user that checking is going on - perhaps even as a simple info pop-up when it starts and finishes.