updating EventQueue to use MultiClassSerializationHelper in itm-utils
bumping netty-protocols version to latest snapshot

1.8-SNAPSHOT isn't available anymore, using 1.9-SNAPSHOT instead
adapting PortalEventStoreHelper to MultiClassSerializationHelper
adding log statements to GatewayEventQueueImpl
making GatewayEventQueue a service in singleton scope hence it should start with gateway and not the channel handler)
starting the EventQueue service
extracting upstream message handling to GatewayEventQueue, informing GatewayEventQueue about channelConnected and channelDisconnected calls
small log statement fixes
stopping GatewayEventQueue on Gateway stop
adding GatewayFailureEvent for gateway local errors leading to process termination.
Renaming UpstreamMessageQueue and adding a safer error handling for queue and channel errors
Adapting the gateways main class to listen for GatewayFailureEvents
adding a test case for the UpstreamMessageQueue
UpstreamMessageQueue should not interrupt dequeue future on channel disconnect

If the future is already executing the onSuccess-method, its better to finish this execution due to the fact that the future enqueues the message if sending fails. Otherwise, if the future is interrupted, messages may get lost.