Implement an Email actor which is responsible for sending emails

Issue #65 invalid
Edward Yue Shung Wong
created an issue

We need to make the email functionality reusable. Following the Akka model, this should be an email actor!

define message interface for Email actor (e.g. EmailMessage object).
consider how to handle different types of email.

SEE - TemporaryEmailHelper referenced by MentorNotificationActor