react-express-mongodb: rename server to backend

The goal here is to keep the same structure than the other examples.
Also, considering that it has a "frontend" folder, the equivalent for
the server should be "backend".

Signed-off-by: Jérémie Drouet <jeremie.drouet@gmail.com>

react-express-mongodb/backend/utils/helpers/logger.js

@@ -0,0 +1,9 @@
+const path = require('path');
+const filename = path.join(__dirname, '../../logs/project.log');
+
+//you can change format according to you
+const log = require('simple-node-logger').createSimpleLogger( {
+    logFilePath:filename,
+    timestampFormat:'YYYY-MM-DD HH:mm:ss'}
+);
+module.exports = {log};