Review page should be per-group

[theosanderson]

I think the review page makes the most sense if it only displays sequences for a particular group. Partly because that would be needed to redirect to the new "my sequences" page, which is per group: #1037. But also because I think it makes the most sense in general: we've always talked about you interacting with the DB as one group at a time.

(Apologies that I didn't raise this earlier)

[theosanderson]

A workaround for MVP that we've discussed previously is limiting users to 1 group per user.

[chaoran-chen]

For a superuser (#785), this would be quite important.