Don't hide congress_message form fields that fail validation

[vbrown608]

When we create a congress_message action that targets specific bioguide ids, we don't make a request to smarty streets. However, congress_message.js still expects location data to be present, so it hides reps' location fields. They fail validation, but are invisible, which is bad. We should display them if location data isn't present.

I think it would be nice to do #380 first so we can test this more easily.

This is somewhat related to PR #387