Basically, this was done by:
1. Adding new class type in [common/djangoapps/student/message_types.py]
2. Adding new files for the ace template in a new directory named
[common/templates/student/edx_ace/emailchangeconfirmation]
3. Removing old template files
[confirm_email_change.txt] and [email_change_subject.txt]
from the directories:
[lms/templates/emails] and
[common/test/test_sites/test_site/templates/emails]
4. Converting the [confirm_email_change] code to use [ace.send()]
1b83f24d3c