Registration / Session tracking timeout backoff

[jmwample]

Issue

As we start to roll out registration caching mechanisms the stations should be able to track registrations / session information for connections that are used or that they are capable of serving, but time out registrations that see no use to limit the overall number of registrations tracked over long periods of time that will never see any connections.

Solution

This aggressive timeout might be something like a bool that, once a positive connection is seen, increases the timeout from a few minutes to a longer extended connection timeout as we now know that the client can and will use the session. We could also add a tag to the registration to indicate if the client intends to attempt to re-use the session. If they are not going to try to re-use the session it always uses the short timeout.