[ENH] Add vars in env to mailer config

[pana1990]

I think is useful add the following vars in .env :

MAIL_HOST                     = 
MAIL_USERNAME           =  
MAIL_PASSWORD           =  
MAIL_PORT                     = 587
MAIL_ENCRYPTION         = tls

And

'transport' => [
             'class' => 'Swift_SmtpTransport',
             'host' => ConfigKit::env()->get('MAIL_HOST'),
             'username' => ConfigKit::env()->get('MAIL_USERNAME'),
             'password' => ConfigKit::env()->get('MAIL_PASSWORD'),
              'port' => ConfigKit::env()->get('MAIL_PORT'),
              'encryption' => ConfigKit::env()->get('MAIL_ENCRYPTION'),
],

[tonydspaniard]

You are right. I'll do.