QPID-6068: [Java Broker] Prevent NPE when ediiting JMX_CONNECTOR port through REST or Web Management UI

* Also hidden the authentication provider field when editting an RMI port
* Added the missing prompts for transports/protocols.
* Remove the mandatory marker from the protocols field

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1622677 13f79535-47bb-0310-9956-ffa450edef68