Email users in the subscriber list, triggered by changes on task-page

[jailuthra]

This will require the following:

• Making email-id a required field while registeration (Take email-id during sign-up, and send confirmation email #3)
• Adding an email function in views.py, and trigger it at every comment on the task-page
• Using the correct library for sending the email, so as to not end up in Spam 😛