Add from name to emails.
Add full name to subscribers.
Rename EmailSendLog table and avoid duplicate rows.
Rename title column of the Email table.
Add a configuration file.
Call all database functions in explict transaction.

Extend the Postgres class from the connection class of psycopg2. Use the
with keyword supported by psycopg2 for transactions.
Add --debug argument.
Add worker.py to send emails.
Rename the default configuration file.