Add errorhandlers to validation app
Add errorhandlers to validation app

To eliminate the multiple levesl of try/catch blocks in the
validation logic, create a few app-level error handlers:
handle_response_execption for uncaught exceptions and
handle_response_exception that will--at least for now--continue
to make use of the ResponseExceptions used throughout the
validation process. Also remove the try/catch around application
creation, since new logging will soon catch exceptions there.

fedspendingtransparency/data-act-broker-backend,fedspendingtransparency/data-act-broker-backend