Added mailer with handlebars and nodemailer

mailer.js

const path = require('path');
const nodemailer = require('nodemailer');
const hbs = require('nodemailer-express-handlebars');

const {host, port, user, pass} = require('../config/mail.json');

const transport = nodemailer.createTransport({
  host,
  port,
  auth: { user, pass },
});

const handlebarOptions = {
  viewEngine: {
    extName: '.html',
    partialsDir: path.resolve('./src/resources/mail/'),
    layoutsDir: path.resolve('./src/resources/mail/'),
    defaultLayout: 'email.html',
},
  viewPath: path.resolve('./src/resources/mail/'),
  extName: '.html'
};

transport.use('compile', hbs(handlebarOptions));


module.exports = transport;