Remove HTML comments from emails

[alexcwatt]

These come through in some clients (e.g., FastMail — and I think I've seen it in Outlook too):

If we need comments, it's probably best to do them Ruby-style:

<% # Comment here, which will never come through in generated view %>

But I think we can just delete these comments. Or maybe we can leave them and do some processing where we remove them before sending the email.