Akka.FSharp api: fixed ask operator (<?) to return Async<obj> instead of Async<unit>
Port Member, VectorClock, Reachability and Gossip
Merge pull request #219 from smalldave/akka-cluster

Akka cluster
ClusterDomainEventPublisher and more
Implement ClusterDaemon (unfinished)
merged with dave's changes
fixed some post-merge compilation issues
ported all Akka.Cluster tests to XUnit
Whoops, left out some files
Merge branch 'dev' into akka-cluster
filled in some missing assertion types to get other Cluster tests to pass
implemented Cluster methods

- Implemented OnMemberUpListener
- Implemented most of Cluster class
- Working on implementing ClusterDaemon
implemented ClusterReadView
implemented GossipStats and JoinSeedNodeProcess
implemented FirstSeedNodeProcess
implemented Cluster wire formats
adjusted the namespace on ClusterMessages
implemented the first half of the ClusterMessageSerializer
finished most of the ClusterMessageSerializer for Gossip
working on adding ClusterMessageSerializerSpec