Clear email address

[C-Carr22]

The problem

When the web page is refreshed the entered email address is still stored in the code, this may cause a problem if a user entered access codes but forgets to enter an email address before sending as the videos will be sent to the wrong email.

What needs to be done

Add function similar to the clear_access_codes function to make sure that the email_address variable has no value when the page is refreshed

To be done by 12:00 09/09/19