Incorrect view of initial contact points when subscribing to cluster client

[huntc]

Akka cluster client does not provide the correct initial view of contact points w.r.t. to another actor subscribing to its events. This is accidental and due to a previous PR by me where the ability to subscribe to notifications was provided. There is a variable named contactPathsPublished which is empty on startup. I see now that contactPathsPublished's initial value should be that of contactPaths, otherwise a subscriber will receive any initial contact points from config, and then ContactPointAdded messages for events regardless of whether they in the initial contact points.

By initialising contactPathsPublished with contactPaths then subsequent contact point notifications will yield ContactPointRemoved for those contact points that are unknown to the cluster client. I see this as being the correct behaviour, and have tested it by copying ClusterClient into ConductR.