Refactor Context::printInputSummary

[jcoulter12]

The print input summary function is very unwieldy and overly complicated as it was at first done by hand.

It should be updated to be part of the checkRequirements function of an app -- any variable which is checked by checkRequirements should also be printed as an input variable at the startup of the app. This would be more manual and would extend naturally as new apps are added.