celery (and kombu) need a new transport and result database when
moving away from mongodb.


-  celery/kombu and sqlalchemy:
   `http://docs.celeryproject.org/en/latest/getting-started/brokers/sqlalchemy.html <http://docs.celeryproject.org/en/latest/getting-started/brokers/sqlalchemy.html>`_
-  whether a database is actually a good event oriented transport,
   is an open question. Maybe amqplib and rabbitmq are the better
   answer?

For the result thing we maybe should really use sqlalchemy?

Goal of this bug:


1. Research options for celery/kombu
2. come to a conclusion what to use
3. Implement it

Minish SQL migrations support (as in, database migrations, not
mongo->SQL conversion, that's a different bug.)

I'm close to being done with this. Track progress here:

[https://gitorious.org/\ :sub:`cwebber/mediagoblin/cwebbers-mediagoblin/commits/sqlmigrate](https://gitorious.org/`\ cwebber/mediagoblin/cwebbers-mediagoblin/commits/sqlmigrate)

I have rebased my exif\_gps-merge branch into
https://github.com/jwandborg/mediagoblin/tree/exif-rebase, please
review and merge :)