Send email route handler

with_mailer_route.js

// server/index.js
const mailer = require("./mailer"); // In the top of the file

/* ... */

app.get("/api/send_email", function(req, res) {
  res.set("Content-Type", "application/json");
  
  const locals = { userName: req.body.userName };
  const messageInfo = {
    email: req.body.email, fromEmail: "info@ingsw.com",
    fromName: "Star Wars", subject: "Checkout this awesome droids"
  };
  mailer.sendOne("droids", messageInfo, locals);

  res.send('{"message":"Email sent."}');
}