Probably should add automated tests before doing the following:
[ ] Use templates for all aspects of it
[ ] Text-only generation should then be easy by just having (text-only) jinja2 templates with the same names
[ ] All pieces should access the one SlackScraper instance and use it to get info, instead of pieces being passed around.
[ ] All pieces should operate based on the date being processed, instead of start or end timestamp. Date info should come with the messages being rendered.
Probably should add automated tests before doing the following: