Support trial run that doesn't send an email

[thashepherd]

As a developer, I'd love a way to run this project without invoking send_email or requiring any external environment variables to be set.

Developing a way to skip email functionality by supplying a flag or argument when running python main.py would solve this issue.

An even better solution would supply (and document!) a way to skip email functionality when running docker-compose up --build as well.