Added optional property (skipSenderNode) to PubSub.SendToAll
if the message should be sent to a matching path on the sender node or not.

Added optional property (skipSenderNode) to PubSub.SendToAll.
Deciding if the SendToAll message should be sent to a matching path on the sender cluster node or not. + Test and Docs.
Minor fixes after review.
Merge pull request #1452 from akka/wip-pubsub-optionally-send-to-sender-node-with-sendall-jboner

Added optional property (skipSenderNode) to PubSub.SendToAll