Migrate away from using natural primary keys

[di]

A number of our tables currently have natural primary keys, such as:

• The packages table (used by the Project model)
• The releases table (used by the Release model)
• (...this may be all of them)

We should migrate away from natural keys and use surrogate keys instead where appropriate, e.g.:

id = Column(Integer, primary_key=True, nullable=False)

This will require a DB migration and possibly a maintenance period.

[steiza]

I'm going to start working on this as part of the PyPA sprints. If anyone is interested in pairing, let me know!

[ewdurbin]

Ah, this is already pretty far along in my court @steiza. Given that it will require an admin to roll out (potential downtime, db backups, etc). I'll continue on it!

[yeraydiazdiaz]

@ewdurbin is there anything else pending for this issue or should can it be closed?