Rework expected values to allow users to skip expected confidence intervals

[kjacobsen16]

From Pete:

I can't input an expected value without expected confidence intervals. While this seems painless, many authors don't actually run an example with confidence intervals, so it would be great if we could add what expected values we wanted to use.

My thinking: we could make none of the expected values required and just check the outputs against it if they're given, but that will probably lead to users never entering expected values.. Marking as enhancement for now since they can use the "skip check" box