BREAKING CHANGE: add back lib/index.js as a wrapper around lib/mongoose.js

Author: vkarpov15

lib/index.js

@@ -0,0 +1,13 @@
+'use strict';
+
+/*!
+ * Module dependencies.
+ */
+
+require('./driver').set(require('./drivers/node-mongodb-native'));
+
+const mongoose = require('./mongoose');
+
+mongoose.Mongoose.prototype.mongo = require('mongodb');
+
+module.exports = mongoose;