JMX status page does not update when a new application is started on previously used JMX port

The JMX status page only looks for new applications to register when a new host with a new JMX port and a new RMI port is registered. If you start a different application on the host using the same JMX/RMI ports it will not be detected instead you will see an error message mentioning that the old application cannot be monitored.
The problem is in HostForwarding where registerRemoteMBeans() is only called on new entries. We need to ask about MBeans oftener and register a proxy whenever a new one shows up.