Adds equals() and hashCode() to MemberIsAvailalble
Properly filter and rearrange events in snapshots

Introduces the ability to inject a filtering function in Snapshot providers,
 allowing for complicated predicates and processing to take place.
Ignores ClusterMemberSnapshotTest since it is now irrelevant. The same functionality
 has been pushed up in HA, tested in HaNewSnapshotFunctionTest
Removes accidentally committed test in ClusterTest