code: function(criteria, cb){
        var self = this;
        waterlock.Auth.findOne(criteria).populate('user')
        .exec(function(err, auth){
          cb(err, self._invertAuth(auth));
        });
      }
docs: Simple wrapper for Auth find/populate method
  
  @param  {Object}   criteria should be id to find the auth by
  @param  {Function} cb         function to be called when the auth has been
  found or an error has occurred
  @api public