Code review comment for lp://staging/~ris/loco-team-portal/fix-552762

> Hi Robert, this MP still need more work, we need to add some lines of codes to
> keep the relation between the venues and the events, i mean this line :
>
> 226 + # Deleting field 'TeamEvent.venue'
> 227 + db.delete_column('events_teamevent', 'venue_id')
>
> we need to store in memory all venues/events relatiosn before then create them
> once the new table TeamEventVenue is created.

I added it, please check it.