shared: Refactor models and reset and squash migrations

shared/migrations/0001_initial.py

shared/migrations/0002_auto_20201007_0933.py

shared/migrations/0003_auto_20201007_0944.py

shared/migrations/0004_article_author.py

shared/migrations/0005_auto_20201007_1028.py

shared/migrations/0006_personpage.py

shared/migrations/0007_peoplepage.py

shared/migrations/0008_personpage_search_image.py

shared/migrations/0009_remove_article_author.py

shared/migrations/0010_article_author.py

shared/migrations/0011_personpage_profile_id.py

shared/migrations/0012_article_date.py

shared/migrations/0013_auto_20201104_1053.py

shared/migrations/0014_auto_20201104_1134.py

shared/migrations/0015_auto_20210106_1029.py

shared/migrations/0016_auto_20210107_1025.py

shared/migrations/0017_person.py

shared/migrations/0018_auto_20210107_1101.py

shared/migrations/0019_personpage_person.py

shared/models.py