rfc2487bis-04: Failed negotiations & virtual hosting

I had a couple of comments on the new draft:

1. You might want to mention what happens if the TLS negotiation fails in a
   non-recoverable way.  In these cases, the connection is simply dropped.
   (Since the encryption is out of skew, there is no way for a client to
   send a QUIT command or a server to send an error back to the client).

2. As Paul Hoffman and I discussed at IETF, there may be a virtual hosting
   problem that will necessitate a change.  For example, smtp.gshapiro.net
   does virtual hosting for about 50 domains.  If a client expects the
   certificate CN and the hostname to match, there needs to be some way to
   communicate that information.  HTTP has HTTP/1.1 or the Server: line to
   indicate the requested server.  SMTP will need the same if the server is
   to be able to determine which certificate to send.