Move initialisation of state serialisers and conduits to Spring
Move initialisation of StateWatchers to spring

The StateObserver interface is modified slightly.  The redundant removeStateWatcher
method is removed and the addStateWatcher is replaced by a setter.
Move responsibility for starting the DataGatheringScheduler thread to that class
Remove dead method
Initialise DataGatheringScheduler as a Spring bean
Remove unnecessary XML-serialiser bean
Move initialisation of default MessageHandlers to Spring
Fix NPE on dga admin commands