Fix lint errors

Created by: dbolson

This fixes all errors from running flake8. I made two errors ignorable:

E126: When a line is split with a slash, pep8 gets upset:

vote = session.query(Vote) \
        .filter(Vote.election_id == election_id, Vote.vote_key == ballot_key) \
        .one_or_none()

E701: Adding types seems to cause this when declaring a variable to have a type

self.weight: Decimal = ONE

Tests continue to pass and the app seems to work when clicking around, so I don't think this broke anything.