message: Update mongoose.js
  The `useMongoClient` option is no longer necessary in mongoose 5.x, please remove it.
diff: const mongoose = require('mongoose');
  module.exports = function (app) {
  - mongoose.connect(app.get('mongodb'), {
  - useMongoClient: true
  - });
  + mongoose.connect(app.get('mongodb'), {});
  mongoose.Promise = global.Promise;
  app.set('mongooseClient', mongoose);
  