Adds an "Is it Friday" service which checks https://www.is-it-friday.org/ to find out if today is Friday (intended as a test of background updating services for a site which does not require an API key or limit requests)
Removes the hardcoded weather service from main.py
Uses the new services.json file to find services, fetch their update() method, and schedule calling that method.
Use of the built in logger rather than direct printing allows for separation of info, debug, warning, and error.
Solves issue #6