Implement Email Notifications for Ticket Booking, Cancellation and waiting list

# Overview

There are emails prepared in certain functions of the files that are triggered when a ticket is booked and when a ticket is cancelled.
There are also emails to be sent to all the people in the waiting list when a fully booked event gets a couple free seats (by others cancelling etc).
These emails have not been sent to the users at the moment. Send the emails with the appropriate subject and content.
There are separate emails for cancellation, ticket booking and waiting list in the code.

# Requirements

### 1. The emails must be sent to the user that has booked at the moment of booking/cancellation/availability of seat.
### 2. It must contain working links to the ticket/login page.
### *Extra Bounty points* if it is a working link on a freehosted server/site.
### 3. *Extra Bounty points* for having the QR image display in the email itself.
### 4. Emails must be sent in a predictable, sustainable manner.