* Format Javascript and CSS files with `prettier`: `prettier --write 'CTFd/themes/**/*'`
* Format Python with `black`: `black CTFd` & `black tests`
* Travis now uses xenial instead of trusty.
* Fix imports/exports to accept JSON
* MariaDB does not properly understand JSON so it must accept strings instead of dicts
* MariaDB outputs strings instead of JSON for its JSON type so the export serializer will attempt to cast output JSON strings to JSON objects
* Update Makefile to not lint any uploads
* Update Flask-SQLAlchemy to 2.4.0 to remove a large amount of warnings