Upgrade django library

[sgowda]

Newer versions of django have built-in support for database migrations which makes it much, much easier to add new columns to existing databases. Of course it is likely that the way that django needs to be initialized is different in newer versions

[TomekFraczek]

This also requires an upgrade of celery to use the standalone Celery 4.3.0 (pip install celery) instead of the Django plugin (django-celery). This in turn requires a re-work of how celery is installed