Merge pull request #248 from Aaronontheweb/master

Akka.NET v0.6.2
Merge remote-tracking branch 'upstream/master' into dev
Merge remote-tracking branch 'upstream/dev' into dev
upgraded Helios dependency and bumped version to v0.6.3
added a wait mechansim for blocking main application thread until cluster shuts down
fixed a bug that caused fallback configurations to be dropped during ActorSystem start
Merge pull request #261 from Aaronontheweb/dev

[Getting ready for v0.6.3] upgraded Helios and added method to block application thread until ActorSystem shutdown