need per-ticket ACLs

[Robert Bruce Park]

Currently all tickets are writable by all bileto users. As the number of users grows, so does the number of people you need trust with write access to your tickets.

Bileto needs to grow an ownership field that would default to some relatively broad team like bileto-users but would allow users to select a narrower team to control the ticket.

It's then possible to call archive.newComponentUploader to grant that team upload rights on the ppa, which would allow us to remove some frequent uploaders from ci-train-ppa-service and just allow them per-ppa uploading rather that total control of the entire world.