Cleanup

Add newlines and project descriptions
First model import
Add SourceGroup model
EventActor model, use entity kinds
Simplified Models, add unicode tests.
Added note about freezegun time
Final initial modeling
Draft of Medium API sans-tests
Subscription.subscribed_entities tests.
Medium.followers_of tests
Medium.followed_by tests.
Medium.get_event_filters_tests
Medium.subset_subscriptions tests
First Event access test.
Tests for Medium.entity_events
100% test coverage
Fix documentation underline length
Remove unnecessary docs line
Remove leading zeros in testing dates
Removed unused autodocs