add settings file for rq worker

add render_template

move action.html

add func: send HTML emails using Mailgun and Python

add func: task queue and setting up a Redis database

add func: send emails with Python and Mailgun

add m

add model changes ang migrations, make sure migrations run before app starts

upd README.md

upd requirements.txt

upd Dockerfile

add CONTRIBUTING.md file

add migrations dir

manually review and modify database migrations

add Flask-Migrate to Flask app & upd requirements.txt