Add the role to the email address, to make filtering easier

Fixes #10
Migration to add last_response_content_type
HTML-escape non-HTML emails
Test to ensure non-HTML response bodies get HTML-escaped

Our first test!
Break apart perform-check round 1
Update gitignore
Further break up perform-check
Mark a few fns as private
Store the content_type of the response in the db

This should close out #11
Add some model helpers
Add a dev-sandbox namespace, so it's easier to jump into the code