Revert "Get closer to making Google OAuth 2.0 work.  Next: move from sqlite to pgsql, as the former has no JSON field type."

This reverts commit 6c8fd1c9fef972efa8f499c49e530e9c7e1d8d00.
Revert "Settings in a separate file. Simplify by creating app factory. Try but fail to get python-social-auth to work."

This reverts commit 5cd9c7a04d7644aaf0763565d6e799009e91a188.