dev_settings: Add EMAIL_PORT setting in zproject/dev_settings.py.

This commit adds EMAIL_PORT setting for explicitly specifying the
port of SMTP provider in dev_settings.py.

We also change email_backends.send_email_smtp to pass EMAIL_PORT
along with EMAIL_HOST to smtplib.SMTP.

After this change, we will not need to include the port along with
host in EMAIL_HOST.

Also updated the email.md docs accordingly for this change.

zproject/dev_settings.py

@@ -89,6 +89,7 @@ PASSWORD_MIN_GUESSES = 0
 # SMTP settings for forwarding emails sent in development
 # environment to an email account.
 EMAIL_HOST = ""
+EMAIL_PORT = 25
 EMAIL_HOST_USER = ""
 
 # Two factor authentication: Use the fake backend for development.