qpid-proton: reactor sends messages in clear if ssl is requested but not available

The 1 proton.reactor.Connector, 2 proton.reactor.Container, and 3 proton.utils.BlockingConnection classes in Apache Qpid Proton before 0.12.1 improperly use an unencrypted connection for an amqps URI scheme when SSL support is unavailable, which might allow man-in-the-middle attackers to obtain...