db.users.find({
  $or: [
    {'backer.admin':{$exists:1}},
    {'backer.contributor':{$exists:1}}
  ]
},{backer:1}).forEach(function(user){
  user.contributor = {};
  user.contributor.admin = user.backer.admin;
  delete user.backer.admin;

  // this isnt' the proper storage format, but I'm going to be going through the admin utility manually and setting things properly
  if (user.backer.contributor) {
    user.contributor.text = user.backer.contributor;
    delete user.backer.contributor;
  }

  db.users.update({_id:user._id}, {$set:{backer:user.backer, contributor:user.contributor}});
});