adding postfix container to send emails instead of using third-party email service

[eoliveros]

• changes to docker-compose.yml:

  • expose 587(internally) to the mail container.
  • comment ports in mail container
  • created link from be_app to mail container

• attempt to get postfix integrated with the beryllium stack

  • install flask-mail
  • initialised flask-mail
  • changed test_email route to use send_mail_postfix
  • copied send_mail function to send_mail_postfix
  • attempts to get the send_mail_postfix running

• added send_mail_postfix function in the email_utils

  • had to change some of the parameters to match flask-mail parameters

• added more variables for flask_mail to run correctly:

  • MAIL_SERVER
  • MAIL_PORT

• added the variables to app_core:

  • MAIL_SERVER
  • MAIL_PORT

• Added an IF condition that would choose between send_mail_sendgrid and send_mail_postfix.

  • needed some work the functions inside email_utils need to somehow match the parameters passed to the new send_mail function which then needs to be passed onto either send_mail_sendgrid or send_mail_postfix

• attempts to get attachment in the parameters for the send_mail function