Send mail with phpmailer and gmail smtp

phpmailer.php

<?php
//add to composer.json "phpmailer/phpmailer": "~5.2"

require_once 'vendor/autoload.php';
$mail = new PHPMailer();

$mail->IsSMTP();
$mail->Mailer = 'smtp';
$mail->SMTPAuth = true;
$mail->Host = 'smtp.gmail.com'; // "ssl://smtp.gmail.com" didn't worked
 $mail->SMTPSecure = 'tls'; // or 'ssl'
 $mail->Port = 587;  //465 for ssl

$mail->Username = "mahedi2014@gmail.com";
$mail->Password = ""; //your gmail password

$mail->IsHTML(true); // if you are going to send HTML formatted emails
$mail->SingleTo = true; // if you want to send a same email one-by-one to multiple users in .

$mail->From = "mahedi2014@gmail.com";
$mail->FromName = "Your Name";

$mail->addAddress("mahedi201422@gmail.com","User 1");
$mail->addAddress("mahedi2014222@gmail.com","User 2");

$mail->addCC("mahedi20141@gmail.com","User 3");
$mail->addBCC("mahedi20142@gmail.com","User 4");

$mail->Subject = "Testing PHPMailer with localhost";
$mail->Body = "Hi,<br /><br />This system is working perfectly.";

if(!$mail->Send())
    echo "Message was not sent <br />PHPMailer Error: " . $mail->ErrorInfo;
else
    echo "Message has been sent";