Merge lp://staging/~james-w/libdep-service/enable-admin into lp://staging/libdep-service

Enable the admin, run migrations on the dev db, and enable db periodic tasks.

Hi,

My apologies for folding things together, but they are all small and
standalone.

While testing the periodic tasks in the db I found three problems:

  1. We don't currently enable the admin area, so we can't easily set
     them up.

  2. We don't currently run migrations for the dev db, so the table
     doesn't exist.

  3. Django helpfully warns us that our settings are wrong for using
     this functionality, so I extended the schema to make the default
     to use the db for scheduling.

Thanks,

James