Add 'suspend notes' for antispam team

By request of @azurelunatic: this will allow the SEO spammer suspend squad of the antispam team to leave notes on particular accounts that are borderline or frequently reported, so we don't have to keep lists of "we decided that account was legit, even if it's high-volume" to give to new people.
I had an ehtml in there in the first round and it wound up double-escaped when I had the system display the note, so something along the chain is already escaping it. I'll try tracing through the stack and figure out where it is.