Data handler errors do not get exposed in the admin interface

[jeancochrane]

Debugging #163 was confusing because errors that get raised by Fobi data handlers do not get exposed in the admin interface, so while the Surveys appeared to be submitting successfully they were raising errors behind the scenes.

This may be a rabbit hole, particularly if survey submission is not tied to form handling. But let's take a few minutes to look into it and see if there's an easy way to run the data handler before returning the success message in the Survey Run view.