code: function listChangesNotInLocalDataset(datasetId, lastSyncTime, clientInfo, cb) {
    async.parallel({
      appliedUpdatesSinceLastSync: async.apply(listAppliedChangeSinceLastSync, datasetId, lastSyncTime, clientInfo),
      pendingChangesForClient: async.apply(listPendingChangesForClient, datasetId, clientInfo)
    }, function(err, results) {
      if (err) {
        return cb(err);
      }
      return cb(null, results.appliedUpdatesSinceLastSync, results.pendingChangesForClient);
    });
  }
docs: List all the possible changes that are not in the current local dataset copy yet.
  It includes:
  - the updates that are applied since last sync loop run from the given client
  - the pending changes that are still waiting to be processed for the given client
  @param {String} datasetId
  @param {Number} lastSyncTime the timestamp of when the last sync loop completed
  @param {Object} clientInfo the client info. Should contain the cuid
  @param {Function} cb