Better email formatting

- author in from field, e.g. "Zach Allaun (via Community)" <bot@...>
- email subjects are now just thread titles
- unquoted post body is the first thing in the email body
Not at all required, but if you wanted to not have to escape the quotes, you could write it like this:

```ruby
%{"#{user.name} (via Community)" <bot@mail.community.hackerschool.com>}
```