Describe the bug
When replying to a thread in the discussion forum, the email notification now quotes the ENTIRE initial post in the thread before getting to the new message. This is annoying when the initial post is very long. The reader of the email must scroll past the quoted post before getting to the new information all the way at the bottom of the email.

Expected behavior
Previously, the quoted post was truncated to a more modest number of characters. We made a change to the formatting of the notifications and unintentionally removed this truncation. Let's re-add the truncation. Maybe 100 or 200 characters is sufficient?

To Reproduce
Steps to reproduce the behavior:

1. subscribe to email notifications on the forum (include self-notification to aid testing)
2. make a new thread on the forum with a lengthy initial post
3. make a reply post with that new thread
4. check the email or email folder on vagrant https://submitty.org/developer/development_instructions/vagrant_email_configuration