Create load_models().

Create load_models().

So all models are ready when connecting to the db and so
our "db" object has all models listed on it, create a
function to load all models from the media_types, etc. Call
it in setup_database()

Problem: This gives celery warnings, because celery is
imported before being setup properly. No idea how to fix
this now. So media-type loading is excluded from
load_models for now.