Added support for computing the RoadStack attributes
.alloweds is a dict of remotes that are allowed (available for tx/rx of messages) keyed by remote.name
.changeds is a dict of two items
plus: is a set of remote names of newly allowed remotes
minus: is a set of remote names of newly disallowed remotes
This will enable the SaltRaetRoadStackManager behavior to populate the data store with alloweds and generate presence events