bug 773522: Fix djcelery tables with a local migration

djcelery has South migrations, now. But, we already slapped South migrations on it in our own local directory. This means some things are broken and DB columns missing, though I don't think anyone noticed until now.

This PR is step 1, which brings our custom migrations back in line with djcelery's official migrations. Step 2 will be to delete our local migrations, once they've been applied, and to let djcelery manage itself going forward.