Paginate front page experiments/workspaces, at least for admins

[zjmiller]

trafficstars

We've scaled to the point where loading the front page for an admin can lock up the app to the point where participants are affected.

[brachbach]

Another option would be to delete or hide some of the old experiments/trees

We could either build that functionality into the app, or it could be a one-time thing that @zjmiller you do with a db query or something