crew repo and bookmarks

[Levi Bard]

> If they're shared, they're pulled on pull and updated on push. The
> only asymmetry is that you have to explicitly choose to share, i.e. to
> clutter everyone else's bookmark namespace. We assume that bookmarks
> that are pushed are meant to be shared with all the repo's users.

(Btw, this is only if you're already pulling the bookmarked changesets.)