[PATCH] support Upgrade header in ssl-bump decision.

When the Upgrade: header is present and indicating some non-HTTPS
protocol there is no reason to ssl-bump. Doing a bump would be
detrimental to the client connection.

This patch seeks to make bump only happen if:
  a) no Upgrade header is present (old-style HTTPS CONNECT)
  b) the Upgrade header indicates TLS/ protocol is being wrapped.

Amos