Add migration (for db, folders...) mechanism

server/models/application.js

@@ -0,0 +1,31 @@
+const mongoose = require('mongoose')
+
+// ---------------------------------------------------------------------------
+
+const ApplicationSchema = mongoose.Schema({
+  mongoSchemaVersion: {
+    type: Number,
+    default: 0
+  }
+})
+
+ApplicationSchema.statics = {
+  loadMongoSchemaVersion: loadMongoSchemaVersion,
+  updateMongoSchemaVersion: updateMongoSchemaVersion
+}
+
+mongoose.model('Application', ApplicationSchema)
+
+// ---------------------------------------------------------------------------
+
+function loadMongoSchemaVersion (callback) {
+  return this.findOne({}, { mongoSchemaVersion: 1 }, function (err, data) {
+    const version = data ? data.mongoSchemaVersion : 0
+
+    return callback(err, version)
+  })
+}
+
+function updateMongoSchemaVersion (newVersion, callback) {
+  return this.update({}, { mongoSchemaVersion: newVersion }, callback)
+}