Added logger for database connections

loggerFiles/dbCon.log

+{"level":"silly","message":"DB connection closed by user","service":"user-service"}
+{"level":"silly","message":"DB disconnected","service":"user-service"}

src/database/mongoose.js

 const mongoose = require('mongoose')
+const logger = require("../logging/loggerDbCon")
 
 mongoose.connect('mongodb://127.0.0.1:27017/trampa-dev', {
     useNewUrlParser: true
+})
+
+mongoose.connection.on('error', err => {
+    logger.silly('DB connection failed')
+})
+
+mongoose.connection.on('disconnected', () => {
+    logger.silly('DB disconnected')
+})
+mongoose.connection.on('disconnecting', () => {
+    logger.silly('DB connection closed by user')
+})
+
+mongoose.connection.on('reconnected', () => {
+    logger.silly('DB reconnected')
 })

src/logging/loggerDbCon.js

+const winston = require('winston')
+const config = require('config')
+
+const loggerWinston = winston.createLogger({
+    level: 'info',
+    format: winston.format.json(),
+    defaultMeta: { service: 'user-service' },
+    transports: [
+        new winston.transports.File({ filename: 'loggerFiles/dbCon.log', level: 'silly' })
+    ],
+});
+
+if (config.util.getEnv('NODE_ENV') !== 'production') {
+    loggerWinston.add(new winston.transports.Console({
+        format: winston.format.simple(),
+    }));
+}
+
+module.exports = loggerWinston