Switch on fax number existence

This PR adds in functionality to check if the fax result was successful.

- If yes, it says so and gives the user a link to view their application

- If no, it presents a screen saying that the application wasn't actually submitted, and explains the reason why (i.e., either the fax isn't configured [e.g., no phone # or missing API key] or the error message from Phaxio) but gives you a link to view your application instead